I don't think there is any need to wait nearly that long.  It's a good idea, but it's not like it's been super thoroughly developed.  If it's only the concept you are adapting you should be fine.

If you were using a setting and character he had developed that would be one thing, but if you develop your own setting and characters using only the concept of "Self Aware Villains" you should be ok.  

The idea was roomies struggling to pay the rent and different sorts of villains.  I don't think it would be proper to use that exactly, but if he doesn't sign back in and reply within the next week or so you should be ok to design a similar but not identical RP.  Perhaps send him a DM so he for sure knows there is interest next time he logs in.

Examples of Other Takes:

Failed Villainous Plot Campfire Stories
Villainy Anonymous Meeting (with Catering Provided)
Recruitment Interview for Entry into Evil Incorporated LLC Industries
Episodes of "Living Evil" on the History Channel
Episodes of "Big Brother But Also We Are All Evil" on MTV