[Jamie]

Not necessary. You can add grain filler whenever you want, as long as it's before your final coat of clear. Now, normally I do the grain filler right after I strip the radio, but this was a last minute change of plans. I was using Walnut Constantines grain filler too.. so it's colored. Even so, you can also add more toner whenever you want. I could spray more toner on it right now, then add more clear if I wanted to. Lacquer is pretty forgiving as long as you stay with the same brand.