Not particularly rare, but I had a meteorite the first spring of my first farm. I'd say it was somewhere around Spring 15-20. The thing is, I was playing a Riverlands map and it landed on the island with Grandpa's shrine. So a combination of factors - largely because I was still a newbie - led to me not discovering it for weeks, maybe even a whole season later:
- not knowing what the explosion in the night was, so I didn't know where to investigate. Was it on my farm? Somewhere else in town? The beach?
- not going near the site, because I figured I didn't need to deal with the shrine again until Year 2
- also... because it was a Riverlands map, there wasn't any reason to go anywhere close to it - no sizable chunk of land to plant crops next to it, etc.
- not knowing until MUCH later that I could zoom out to see more of the map
- not yet using the wiki or forum
Also, because it was my first playthrough, my progression was... inefficient, to put it nicely. So when I FINALLY found the meteorite, I was unable to crack it open with my copper pickaxe. I upgraded to steel, and anxiously waited for Clint to finish the upgrade, only to find out that steel still wasn't strong enough either!
When I finally broke it down, I was thrilled to get iridium ore, but it would be quite a while before I would get more of them (again, stunted learning curve on first playthrough). I made a sprinkler with them, but wasn't able to make any more for a quite a while after.