I'd like to chip in with my experience and this quote from Stumacs instructions:
OK, last part first: You do not need to sand between coats to get adhesion. That was common with older type of water based finishes, but the modern once doesn't need that. Its not a problem if you do it but it isnt necessary either. I haven't done that for the past 10 years and I have not had any problems at all. And I have used both colourtone and KTM-9 from LMII.
And now on to the "time between coats" part. From my personal experience I'd say do not under any conditions spray coats with less than an hour between coats. It will cause a poor curing process and it will introduce a bueish tint to the finish (maybe not a major problem with this particular guitar). The finish will also be soft and gummy. Take it from one that has stripped off one too many finishes because they turned blue and soft from spraying coats to tight. As a minimum I try to have at least two hours beteeen coats, and no more than four coats per day. If I apply four coats in one day, I also try to leave the guitar for 48 hours before I aply more finish. Of cause it all comes down to thicknes of finish, drying conditions etc, but if you apply a good coat (no orrange peel from spraying too dry no sags or runs from too wet) you will need sufficient drying time between coats and my personal rule of thumb is no less than two hours, especially in dry, hot weather.
And if possible I leave the guitar for at least 3-4 weeks before buffing as the water based finishes continue to cure ofer time and a harder finish is easier to buff and the end result will be better with a harder finish.
thanks Peter, that definitely gives me something to think about....