Hi Alain, my suggestion is to attach the tracks to the lower hull now. In my view it is easier to fiddle around getting the tracks on with the top off and without paint - you can glue them in place if necessary with CA glue without fear of messing up the paint job, and without worrying about snapping off idlers and difficulties aligning sprocket teeth with track holes etc.
Once glue is all set on the tracks prime the lower hull and tracks.
Then paint the wheels and hull sides with the base colour.
Now mask off the wheels and the hull with tape / paper / foil / blue tack, etc.
Paint the tracks in your favourite track colour, brown-grey etc. then do your track detail wash etc.
Now paint the tyres - fiddly, but don't worry too much about the inner ones where you can't see it, and you can always touch up bits later.
Now attach the hull top and make good the big joins at the front and nose.
Mask off the tracks and wheels and paint the rest of the tank in base colour.
When the paint is set remove the masking - and it's all done!
I got this method from Mig Jimenez's FAQ; you can see how I used in on my Panther at the end of page 1 / start of page 2 of the thread
Zvezda Panther D - without glue? On that kit there was almost no choice because of the track system, but I would definitely try it this way again even with vinyl tracks on a small scale model - I think it will help avoid that look that many small scale tanks have of the tracks really looking they were added afterwards, and the tank not sitting on them properly.
Take the plunge and good luck...