I had the tranny on my 90 gxe rebuilt last year (140,000 mi.) right about
the time it was doing the same thing as yours.  After the rebuild, the
shifting was very crisp, but when I first start it up (cold) it also
hesitates to drop into 1st gear from Park.  I took it back to my rebuilder
and after a couple of days, he discovered that another customer w/ a Stanza
(same basic transmission) was doing the same thing until the tranmission
controller (electronic controller unit) was replaced.  So what I do is wait
a few seconds until I feel it drop into 1st when cold before hitting the
gas.  If I don't, I find myself starting in 3rd gear and I know that's not
good for the tranny.  So when that happens, I immediately shut it down,
restart and then let it drop into 1st.  As long as this happens, there's no
problem during drive time.  I won't replace the tranny controller until it
gets REALLY bad!

Chris
90 & 94 GXE's