I have “glassed” a lot of things over the years. We did the one step and while it worked ok, doing it in two or better yet three steps will yield a better product IMHO.
Now let me back that up with why I think so…
Do the top first. Let it cure overnight.
Pick a side then rest it on half the mold. Save pieces and create two sides as halves.
Once that side is done, 180 it after an overnight cure and do the other side.
Why? One word – gravity. Epoxy tends to self level. By placing the working surface more horizontal you get less runs. More so you can also work with the glass in sections and that makes a HUGE improvement. When we did the bottom and transom it came out far better.
Here is an extra hint – use tape to define the edges of the glass, bring the fabric just over the edge and then cut after it starts to cure and remove the tape, then wipe with denatured alcohol and a toss away rag. the overall finish will look more pro and be a LOT easier when it comes time to sand nad varnish.