How long should i wait before joining a campaign?
you should first increase your rank, so that you can join campaign, mostly they require member rank, but in altcoin, there are lots of campaign for jr. member rank
You need 6 weeks since the day you created your account to become a Junior member. Of course, you have to post at least 30 threads to get 30 activities, which is minimum posts for being considered to rank up to Jr. member. Additionally, most of bounties require participants are Junior member (at least) to join. Sometimes, they will accept newbies, but very rarely.
Junior member doesn't require your account has merit points. Only Members required those points. So dont worry too much, after reaching Jr. member, you will have to face with more difficult challenge. For now, take it easy because you only need to move up to Jr.Member from newbie. It's easy.