24 hours before my BA flight, I will actually be in the air on another flight. I am thinking that I can have my wife do online check-in for me at that point, so I can choose a seat assignment. Then, I won't have the printout. I can re-print my boarding pass at a kiosk in Heathrow, correct? Even though I have already done online check-in earlier?
How far in advance can you print your boarding pass at a kiosk? 24 hours just like online?

Thanks

Yes, you can re-print your boarding pass at the kiosk. I'd also advise you to consider using a bag drop kiosk if that service is available.

Realistically, are you going to BE at a kiosk more than 24 hours in advance????

Well, I arrive at Heathrow at 2pm, and leave the next day at 1pm. So, if my wife doesn't check in online for me, I thought that as soon as I stepped off the first flight...I could go to the kiosk and do it. My main concern is getting a decent seat since they don't assign ahead of time.

When you check in online, you do not have to make a print out of it. They can give you one at the airport - but you have saved your seat and officially checked-in.

I found it somewhat interesting that departing certain airports on BA, you CANNOT get your boarding passes printed even if you do OLCI. I flew out of Naples last week on BA, and that's one of those stations.

Anyways, did OLCI from my hotel about 20 hours prior to departure and got very good seats on the full flight to Gatwick.

Your wife would need reference number (usually six-digit combo of letters and numbers). Just be aware of time differences--24 hrs before departure time in the local time.