As it's your FIRST build (Congrats, BTW!) I would have to say paint most parts while still on the sprues. Keep in mind you'll need to scrape the surface to be glued before gluing, but, on the whole, I think it will serve you better.
When you're more set up for the process, you can change the technique, but, for a first kit. Paint parts first.
My advice.
Welcome to KitMaker, man!
Cuhail
