0 Days.

Seems excessive and you're bound to find spoilers all over the Internet regardless. Best solution to avoid them is to not seek out content related to what you're trying to keep unknown and this applies to all things not just RimWorld.

0 days. It's not a story driven game.

6 months?

Should give plenty of time for people to do a playthrough or 2 and plenty of time for data miners to see how things interact on a code level.

As we've kind of reached a stalemate here, I think 2 months is a fair compromise. It's 3 against three in votes, but a lot of votes in favour of 0 days in the comments, 2 people pro 6 months and 2 against.