no, there's no SOP for starting RRs that i know of. usually, they're done on IRC, but there were several groups who did them, each with a different way. some plotted things out in advance, then took turns writing them. others just got the group together and passed things along from one to the next.
the former is more likely to result in a better story. it's also far more likely to result in a
completed story.
the latter method is far less predictable, but also (imo) a lot more fun.
as for boards round robins, house of cards is the first one in the fandom, as far as i know. it was an experiment. worked well in the beginning, but lost momentum. one or two people have expressed an interest in reviving it, so it may yet come to something. heck, i just might step back in and write the next part myself.
anyway, there's nothing that says you can't have 2 RRs going at the same time. nor is there any sort of standard set of rules.
basically, do what works best for you. just know that there's always a chance things may not work out. there's an even bigger chance that they won't go as planned. to me, that's the fun of doing things on the fly, but to others it can be frustrating and disappointing (okay, yeah, it can be frustrating and disappointing to me at times, too).
so, good luck with whatever you decide to do.
oh, and if anyone wants to pick up the house of cards, be my guest.
Paul