Yes, I asked their advice, but now I wish I had used sanding sealer or grain filler, even though it was already treated. The sides are like a pro job, but the front and back are stippled with tiny grain marks. I would use most of the colour coat and maybe not bother with the lacquer. Any sanding after the initial prep is literally a gently rub over to make it feel smooth.
I did get two runs, both of which I was able to sand out after an hour's drying time, then respray.