Its been many years since I went tubular. Tubasti was the glue back then. I had a a few roll off causing spectacular crashes.
What I found worked best for me was to prepare a new rim by using a medium sand paper and effecting a cross hatch pattern on the rim surface, then using electrical contact cleaner to remove any finger prints. This gave the glue something to stick to.
This may not be the right way, I applied the glue and installed the tire, added some air and straightend out the tire.
One thing I remember is, the tire needs to be stretched and tested to make sure it will go on the rim before the glue, or you will have a mess.
Don