This is IMPOSSIBLE to answer unless you tell WHERE your bees are located, as
almost all medications are temperature dependent.

Further, why are you treating with Terramycin?  If your bees are exposed to
AFB, how are you going to identify that fact if your bees have been treated
with Terramycin?  Terra. HIDES the symptoms of AFB, and that is the "evil" of
using it.
I have NEVER used a single dose of Terramycin in 70 years and usually had
100+ colonies.

My bees are close to Washington, DC.  I treat all my colonies with Fumidil-B
every
fall, beginning near the end of October and through the entire November in
order that
the fumidil is stored in the winter food supplies ALL WINTER.  I don't like
feeding in
September, because not much of the treated fumidil sugar syrup will be stored
for the winter.

The very BEST time to use Apistan is during that period when the queen bee has
dramatically reduced her laying of brood or stopped completely.  Here, in
central
Maryland, queens have reduced there laying by October 1st, and completely
stopped
laying by November 15th.  Hence, I install Apistan on October 1st, and
DEFINITELY
remove it by December 1st to avoid any chance of causing mite resistance to
Apistan.

I hope I have helped.

George Imirie
Certified EAS Master Beekeeper
2002 was my 70th year of beekeeping in Maryland and Virginia
Author of George's Monthly PINK PAGES
Author of American Beekeepers Federation HOBBYIST HELP article
Past President of Maryland State Beekeepers Assn.
Just an OLD, RETIRED, SCIENTIST.