I don't know what is the limit, since I never tried, but I think I should give you a suggestion to not post all the skins one minute after the other. Some people, not me, could see this as Spamming skins and it might give you some problems. So yeah I suggest you post one each hour, or each 30 minutes, just to make sure no one thinks you are spamming stuff...
By the way, I didn't know about PMC's anniversary. When is it exactly?