I usually start in 1 change of 95% or even 100%, since the tissue
is ready for the next change, if you have done a good rinse with 95%,
postfixation.  Depends on the size of the tissue, small, tiny mouse
tissues are processed shorter times, 30 min per change, larger
tissues are 40 minutes or so.  I am careful to not overprocess and
the tissues section nicely.

Since my VIP has 4 paraffins, I usually make sure the total time in
all paraffins is 1 hour (30 minutes per change or less).

Gayle Callis