I just got eggs from a first time female that I started pairing up in March since she wasn't up to the proper weight last fall. I did not use a night drop in their case (although I usually do when pairing more than one female just for good measure).

You can pair up your BP's anytime of the year. Some people say they are more successful when pairing in the fall (as this is the time in the wild during the the rainy season in Africa when they start breeding).

Personally I like to start pairing the majority of my BP's in December. If I have any females that are under but close to 1500g I'll wait until spring to introduce a male.