Hello, I'd like to achieve "Perfection" as fast as possible, using 1.6 default rules and without "exploit", but with as many reset as needed (because I guess I'll have to practice a lot, specially for fishing catfish).
I'll try to answer the questions that you have or give some comments.
My background: I'm a casual min-max'er and by no mean I'm good at min-maxing. I'm probably better than 99% of Stardew valley players. However, in the min-max player base, I'm definitely in the bottom tier.
First of all, I'm not sure to what extent you consider an exploit is. Personally I use hammer special skill and animation canceling, which many people consider as exploit or even cheat. I don't do step counting to manipulate the daily luck. I do reset days, but not often.
1) Days 1-10:
Make money by fishing in order to unlock the bus, upgrade the pickaxe to iron (gold ?), craft bombs
Reach mines lvl 120 to unlock the Skull Cave key
Fishing day 2-4 is fine. But once you get the access to the mine, it's better if you do void spirit+diamond farming than fishing. The money you get from void essence + diamonds is most likely more than the money you get by fishing (unless you get godlike RNG with the treasure chests). In addition to that, the combat exp is critical to unlock the explosive ammo recipe. Explosive ammo is really good for skull cavern dives.
2) Days 10+:
- Farm the SC to buy startfruits, reaching lvl 100 asap then farming iriudium while going down.
- Craft A LOT of furnaces to melt the iridium.
- Craft A LOT of regular sprinklers and/or iridium ones
- Buy starfruit with the money from the SC, plant them in the farm
- Plant and tap oaks to make A LOT of kegs to turn the starfruits into wine
Yeah that's the general idea, but I need to add a few things:
- Since you're going Joja route, you need to unlock greenhouse, quarry, panning and go to ginger island ASAP. Craft sprinklers or get the sprinklers from treasure chests and plant starfruits in ginger island + greenhouse in mid/late Spring. You need agriculturist profession before your plant your starfruits in your main farm.
- Don't forget that you also need to buy deluxe speed gro fertilizer, not just starfruit seeds.
- You don't need to craft any sprinkler at all to water your starfruits in your main farm. If you really plan on reseting days as many as needed, might as well force rain totems from the skull cavern's treasure chest.
- I don't know what's the newest meta for 1.6 minmax, but from my experience, I think it's worth it to unlock the mining mastery ASAP. The statue is amazing especially if you get +1 ore buff and the heavy furnace is fantastic for both saving time and money. If you want to unlock the mastery, it means you have to get as many Woodcutter's Weekly as possible during the Desert festival. Fishing XP may be tricky though especially if you decide to go for void+diamond farming instead of fishing in early Spring.
While I do understand the core concept, I don't know how one could manage to make enough money to buy the waivers (~50M) in Y1.
Since every stafruit wine earns 2750 gold, that would mean planting/kegging around 15K stafruits within less than a year, which seems absolutetly unfeasable.
The number of plantable tiles on the base farm is ~3000, which would make around 2 * 2750 * 3000 = 16M per month, which could match the 50M goal.
I don't know how much money you need for waivers, but I assume you don't need 50M since you can cook/ship/craft some of them and then you buy the waiver for the rest.
If you use rain totem, you can plant like ~3.4k starfruits. Also, you can have 3 batches of starfruits instead of 2 if you use deluxe speed gro + agriculturist profession. Don't forget about pumpkin in the fall as well. Pumpkin juice/ pickle is also a big chunk of your money maker.
However, is it even possible to:
- Craft and place 3K kegs ? If not, then the profitability will sink.
It's possible to craft that many kegs but it's difficult. You need to plan it carefully: When do you start planting the acorns? How fast can you get your oak trees going? Remember, you need to chop down your mature oak trees so you get 2 acorns each and then replant it. Can you afford to buy stones for the tree fertilizers while also saving money for starfruit seeds? Can you afford to buy the materials for tappers while also buying the starfruits? And then you need tons of money to buy the woods, copper ores, and iron ores for the keg.
How much can you earn on a typical SC run ? Is it more than what is required to buy all the necessary starfruits and equipments ?
I never really calculate how much money I earn each day as I'm a casual minmaxer. For each run, I get at least 1k iridium ores but I don't remember how many explosive ammo I use each run.
Is the money enough? For me, I never had enough money to buy the starfruits so I always went with melons first batch and then partial melon+starfruit for the 2nd batch, and then full starfruits for the 3rd batch. That's why earler I said that I'm in the bottom tier among minmaxer.
I saw someone mentionning that they were trying to complete perfection run as early as summer Y1, and I also wonder how this could be possible.
I don't know what their strat is, but I suspect they're going for starfruit jelly instead of wine. My guess is they will try to craft, ship, and cook as many as possible to reduce the waiver cost as much as possible and then they will buy the waivers with the money from the jellies+iridium bars.
Closing words:
I suggest you watch this
video to see how cordite got 81M by the end of year 1 in 1.5. Basically everything that I said here is the technique that I learnt from cordite's run.
It's not easy to do minmax-ing like that, but I can tell you it's quite rewarding when you see you have tens of millions of money before year 1 ends.
You are an iridium quality LEGEND! 
