airberlin topbonus - seeking advice for BA reward flight TXL-JFK

My husband and I are meeting for a long weekend in Berlin in October and would like to return to NYC together. His firm purchased his AB biz-class ticket, so the date and flight are fixed. (He asked for BA, willing to change planes LHR, but it was too expensive.) I booked a BA reward ticket in economy for his AB flight, because it was all that was available. Any thoughts on the best way to upgrade? I will keep checking online...is there an optimum time of day to do this? I'll be flying BA (Club Europe) from LHR to Berlin. Any advice on whether lounge staff or sales staff could assist? Many thanks.

If I understand correctly, you are booked on a BA issued award on an AB flight in economy.

Upgrading this ticket will probably only be possible by changing your award ticket - and this will only be possible by calling BA. I would guess that a few days before the flight inventory should become available if enough seats in biz are unsold. I would try daily from 14 days before the flight, with good chances at about 5 days before the flight.