That is a good tapering schedule, and he will probably start you on the lexapro while you are still on the lower dose of zoloft.
It sounds like your doctor knows what he's doing. Yes that's a good tapering off method. However, you may experience some inevitable anxiety. You may want to ask for a presciption for a kalonopin or xanax while you are making the switch.
That taper sounds correct. I was on Lexapro for a few year and I tapered the same way. Lexapro takes about 2-6 weeks to take full effect so you may want to ask your doc about that time between. You will have something in your system though so I think most likely you will be ok.