Wow, first time airbrushing acrylics and you've chosen the most difficult color!
First I would suggest using Tamiya rattle can Aircraft Silver as a primer. This not only gives the fuselage a more realistic bare metal look, but the silver helps the white paint appear whiter by raising its reflective quality.
White pigments require multiple coats before actually appearing white, let alone glossy. You'll require many coats before you're satisfied. You won't, or at least shouldn't, need Future before decals, but there is no reason not to use it after the decals are on. In fact, concentrate on getting a smooth finish that has full coverage, and let the Future create the gloss.
The ONE time I used gloss white, I sprayed the first coat using flat white after the primer. Flat paints tend to be more opaque than glossy paint, and anything you can do to boost the opacity is recommended.I do this with yellow paints, as well.
Allow 24 hours between coats, and a further 48 hours before decaling. Future is a slow curing acrylic and 48 hours is suggested as a minimum before additional coats or handling.