One issue is that fillers are harder to work with in cool weather (below 60). See http://www.westsystem.com/webpages/userinfo/moreinfo/coldtemp.htm for instructions on how epoxy can be used. When you''ve read this article, you might decide it makes more sense to do such work in the Spring.
I assume from your question (I apologize if I''m wrong) that you haven''t done this before. I gotta say in that case, I hope your new boat is neither too big nor too expensive. Frankly the the best amateur paint job I''ve ever seen was so-so, and the worst was shockingly awful. I recently painted a son''s 10 foot turnabout and the results were in somewhere in the middle (the next one will be so-so!), but ok for a $1800 boat. Be sure so-so would be good enough...