Total goose newbie - when to collect or leave Sebastopol eggs for hatching?

I am experienced with chickens and ducks but a complete newbie to geese. A pair of Sebastopols was gifted to me last weekend. I know they are a bit older, probably around 8 years, and I know I can expect few eggs, so I want to maximize the chances of hatching whatever I can. I'd be thrilled to hatch 2 or 3 goslings this year. I've been told that you must collect the first eggs if you don't want them to stop laying and sit, so I assume I need to collect what I can to incubate myself before letting her sit. What I don't know is (1) when can I expect them to begin laying, and for how long; and (2) how do I know when to stop taking up the eggs and leave them for the goose hen? Their prior owner told me she is a very broody girl, and that this pair are excellent parents. Her method is to hand-rear all goslings for the first 2 weeks and then give them back to the pair to raise.

I'd love to hear what other Sebastopol owners do. I know these geese are a bit of a special case because of their typically low fertility and few eggs, and with this being an older pair I assume I can't waste a single egg if I want any babies at all. I'm just trying to figure out the logistics of it all.