I think in general terms the best time to start getting your coop/barn upgrades for a relaxed but efficient CC playthrough is around the 10th of summer.
Barn/Coop
Yeah. Building Coop, Barn, and Big Barn starting then (mid-Summer) and Big Coop a little later to fill with animals later is the relaxed efficient approach to get a Greenhouse before Winter comes (maybe Fall 10-14).
Animals
- Cow, Goat, and Brown/White Chickens around Summer 27 to get you on track for Large products.
- Duck around Fall 6 since you don't need a Large Duck Egg.
Then close your animals in at night (not important; just for your own convenience) and let them out in the morning to graze happily after you pet them.
Oak Tappers
It's really nice to be able to have a Greenhouse on Fall 14th so you have hundreds of thousands of gold on hand by end of year. Of course you also need lots of Kegs to do that, which requires planning for tappers on Oak trees from Spring 1. A dozen Oak tappers around Spring 19 is good enough assuming you'll add a few more each week.
Wood->Axe
Drop off your axe for a copper upgrade on Vincent's BD Spring 10 to upgrade while you mine. This is important for Tappers and Kegs.
Ore->Pickaxe
Drop off your pick for a copper upgrade on Spring 12 to upgrade during Egg Festival. This is important for Tappers and Kegs.
Museum/Mining->Backpack
Don't rush dive The Mines. Get the ore and the goodies on the way. Floor 80 around Spring 26 is fine. This means Floor 30 Spring 10-ish and Floor 50 Spring 16-ish.
1) This gives you days to fish for gold and treasures.
2) Upgrade your backpack to make room for the goodies in The Mines as soon as you have the gold. No hard date.
Fish for Gold
Fish 'til you drop Spring 2-4 at Fish Shop with Training Rod for Perfects (experience, not gold!) then Fiberglass Rod for speed to level up your fishing to 5 or near it the night of Spring 4.
Crops
Spring 1: Limit to 15
Spring 6: Limit to 40-60
Spring 13+: Limit to 80-120
Summer 1: 96 to 128 crops including 60 to 80 Hops (5/8 hops).
If you use the lower numbers, Kegs won't unlock until around Summer 20, which is okay for relaxed play. You still can get 200kgp per month from there on with Pale Ale.
Farm Cave
The Fruit Bats are really handy to get a Greenhouse. They will likely give you 2-3 tree fruits for the Artisan bundle by Fall 14. You also don't have to check them often, which is relaxed.
Gifting
Don't sweat gifting and Help Wanted Quests except birthdays until after the Luau.
Travel
It's easy to repair the Minecarts in the last week of Spring. This makes travel a lot easier. The horse is fun, but a bit of a hassle. I haven't tried coffee.