You'll save wear on the motor and belt by starting up the platter by hand as you turn it on. Also, leave it on even while changing records unless you're using an after market clamp, which, of course, would preclude this.
FWIW the squeak is caused by the belt streaching against the platter at startup - much like your car tires will squeak if you apply too much gas on start up. Piedpiper's suggestion is a good one - it will minimize wear to the belt from stretching. Not a big deal at all.