Yes, I've done this twice this year, @ MIA for a MAD-LHR flight and @ LHR for a HAM-LCY flight, both for the following day but within 24 hours. There's the customary BA eyebrow raise, followed by a lot of typing and flaring of nostrils, but the boarding pass should be printed without too much bother. In both cases i'd already OLCI and just wanted a real boarding pass (can be easier sometimes at outposts than fiddling with the app).