There are lots of diffent ways to glue-up tires. Putting 4 or 5 layers of Mastik 1 down on the rim and more on the basetape is just the way that I (and lots of others) were taught to do it. I have had great success with that method and will continue to do it that way (and will advise others to do so, as well). Having said that, I do not believe it safe to try to ride a tire that was just glued. Nor would I suggest that trying to ride a tubular tire on a clincher rim is safe (for 2 weeks
A great man once said 'you can drive your car with your feet if you want to, just because you can
doesn't make it a good idea'. I would suggest to anyone new to tubulars that the same 'rule' applies. I know a guy who puts the tires on first, then 'pumps' the glue under the tire. Just because he has not had a dramatic 'off' (yet), docent mean everyone should do it that way.
Stretch your tires before you try to mount them. Put glue down in several, thin, even layers on a clean rim (no need to 'sand' them) and the basetape over a period of days. Can you 'get away' with shortcuts? Probably, but if you want the confidence to dive into a corner inside a bunch of other guys in a crit, or across a lumpy, off-camber corner on a storming descent it will probably help you to know at you have done everything possible to ensure your safety and the safety of those around you.