With whitewood I'd process the staves into roughed out bows asap. Many people would leave them outside whilst its cold, I wouldn't. Insect infestation isn't likely to be a problem in the short term, but what if it rains? Rot can still happen.
The way I look at it is you are going to need to do the work of debarking, reducing the stave, sealing the ends etc some time. The longer you wait the more chance of it getting ruined for a bow. Getting bark off is easier with fresh cut wood, even if it is winter. Leaving it on and not storing it properly, well you might forget, and then not get around to doing it until its too late. The bugs have gotten in, drying checks have gone deep, or rot has set in.