I would second those comments. I am also on my 3rd pair of varifocals, and it took me a couple of days initially to get used to them.
Two things I have learnt through experience:
Buy good quality lenses. The ones usually offered by UK chains are cheap and nasty, and if you look at the optical profile there is a lot of unusable area around the edge of the lens.
Spend some time with the optician working out where you want the transition point, that is the point at which it moves the focus from near to far. I found when I was lecturing , using an autocue etc that I needed a much higher transition point than normal, ie more of the lens was dedicated to the close up focus point.