I use canvas stretcher bars or cheap pre-mounted canvas box-frames (3/4" deep side). The largest I can get a decent result with from an A3+ sheet is 16"x12" but that does need putting in a box frame as the long edge is stapled on the outside. 14"x11" with 3/4 inch deep edges allows a complete wrap and looks tidy without the box frame.
I start by stapling the centre of each side, pulling tight, then move to the corners. You will need to find the tidiest method that works for you, it is too easy to end up with an ugly bunch but I find pulling the centre of the corner tight diagonally works for me. I then make a sort of "hospital corner wrap (easy to do, impossible to describe).
Finally I work the edges taut, stapling from the original centre staples out toward to the corners.
I varnish next (usually two coats) and when dry put in the tensioning wedges in the back of the frame.
Seems to do a nice job ( so much so that I've been asked by a friend to mount some of his canvases too!)
I reckon its about an hours work in total.
Hope this is of some use, expect to mess up a couple of times but if you are careful you can always get the canvas off and start again.
Watch the surface of the uncoated canvas by the way, I've knocked off the odd flake using several different canvas materials, including the HP version. Once varnished they seem pretty robust.
Good luck and have fun