3 weeks post. Is this ectropion? (photos)

Ectropion following lower eyelid blepharoplasty is uncommon but can occur.  It can be temporary and related to swelling.  The first method of treatment is exactly what you've mentioned with massage, taping and patience.  This can correct minor ectropions and improve lid position.  
I would recommend continued massage and taping at this stage, but consideration towards revision surgery could be considered if the problem does not resolve.  It's hard to put a timetable on when that could occur as every situation is different but on average, if it doesn't improve by 6 months you could consider revision surgery.  Definitely keep following up with the surgeon who did your operation to optimize your result!
Good luck with your recovery!

With a lower lid ectropion it is important to have close follow up with the plastic surgeon so that they can make sure all the conservative measures are being taken to resolve the ectropion and to protect the eye. The plastic surgeon would want to make sure you are closing your eye to protect the cornea so you do not have ulceration.