I think it is a great idea to relactate to provide milk for your child, whether it's given in a cup or not.
I relactated (much earlier) and it took 3.5 weeks of pumping (15min maximum) 7-8 times a day, never skipping the nights, to get my supply fully up. This was after a 3.5 week period of not breastfeeding. The rule of thumb that was true for me is that it takes the same amount of time to fully relactate as the duration of your break from breastfeeding. (I think this is very subjective though.)
I used domperidone at some point but it was already clear that the pumping was doing it's job at that point. I don't think any of the supply remedies were significant in my case.