Wet sand the primer with 800 or 600+800grit after 24hrs.
For best results, redo your masking at this point as well
However I'm not sure about 2 color coatings or 1 coating?
Probably 2 light-mid coats for a silver. Never a problem going more.
Also Does this stage require 1 coating or 2 coatings?
I like to do 3-4 clears, go lighter than you think and put down more product over more coats. Less likely to get runs, and its probably better to have a bit more material your first few jobs because you'll likely need to do quite a bit of correction.
I'd highly recommend spraying the colour and the final clear all in the same day.
Make liberal use of tack cloths
and for God's sake make sure you have a very high quality mask and
you know how to fit it right. 2/3 part clear coats are absolutely horrible for the body and if they get in your lungs at all, even in a tiny quantity, they will never
ever get out. You want to be using filters with an organic rating, like 3M's 6001 for example. PLUS these filters only remain effective for 24-48 hours after you open the package, so maybe get a couple sets!
I'd highly recommend trying a spray job on a stainless steel water bottle or three before moving on to a bike frame. You need to learn your guns/cans before moving on to very complex parts like bikes.