If you can, you'd be better off gene machining the steadfast bee up to max fertility too, before starting. Otherwise after the first generation your princess has a 50/50 chance of losing that as its active trait. If you can't, then I'd recommend putting it off for now.
Once you have enough wintry/steadfast hybrids start throwing them in the isolator.
Once you have enough wintry/steadfast hybrids start throwing them in the isolator.