869 seedlings!? Holy cow! I started 24, which is way more than I have room in the garden for, lol! I could use about 14 of them, maybe 18, tops. Didn't even start any zukes - I figure I'll just put those right in the ground.
I thought of you yesterday as I was trying to transplant my seedlings into larger pots (looks to me like I should have just started them in larger pots in the first place). It took me 30 minutes to do five! haha! I thought "I'll bet goldenoakfarm has a method that would make this look absurd." The mess I made transplanting those five was ridiculous - dirt everywhere. It was shameful! It was also too early. Next year, I'll try just starting them in three inch pots in the first place. I'll also label them more clearly - I can't tell one type of tomato, pepper, or eggplant from another.
I avoid transplanting into larger pots at all costs because it stresses the plants. I just plant in large pots if they will need them. And I label really well, as I have no memory.
But at least you have stuff in the ground... none here yet... so far behind...