So if I like on facebook and follow on twitter a few months ago or yesterday are the same thing?

Yes. As of now new applications are closed already.

What about in the signature case? Minim 50 posts? weeks? or both?

All members need to post at least 50 posts by the time the ICO ends to be eligible for a reward

https://blog.wavesplatform.com/signature-campaign-details-e66628f761bf#.6ww0png3z

50 posts?
I joined 30 mei, certainly not able to post 50 times while ICO ends

you joined on 30th may? you should have joined even more earlier, you can't post 50 posts in just 2-3 days without spamming.