Hi,
This may be a really dumb question.
I am flying Dublin->London Heathrow->Vancouver on one ticket - All booked with BA.
However, the first leg from Dublin is on an Aer Lingus plane with a BA code share flight number.

Can I check in online for the whole journey (both legs) at one time? I assume I would need to wait until 24 hours before the London->Vancouver flight time for this to be open for check in?
Would I check in on the BA website or the Aer Lingus website?

Thanks