My method (and I am not too much experienced with this really) is to put the medium, then the seeds in a plastic bag (small) then I squeeze out the air and then tape up the plastic. That is it! I'm about to open bags of my stratified seeds in a few days time, actually it is out of the ref already but I am slowly making it get used to room temp by exposing them in airconditioned air at night for a few nights. Just a precaution that I want to do, I think it might not be necessary. I just feel it's a way to gently wake them up.
TTFN
Arvin