If the breeder thinks the little one will wean in 7-10 days, my guess is it's only on one feeding a day, and I would definitely ask the breeder to show you exactly
how he feeds the little one, so you can follow the same method. If you do it too differently, the conure might decide it's too different and refuse it. Don't be too surprised if the little one weans in a few days and loses some weight, as opposed to the 7-10; birds are known to stress wean, which means when they have too much stress of going to a new home, they will wean themselves quickly as a survival mechanism. Midge did that to me, I brought her home on one feed, she ate once, and that was that
Do you have a scale you can use? Really, I think that would be your most useful tool of all, so you can monitor the weight of your little one and keep an eye on it. Weight Loss during weaning is the biggest problem with the little guys, and it'll let you really monitor your birds health. I would weigh him every other day or so, until he maintains a steady weight. Then you can go to once a week, then once a month...
Since it's a MBC, you can use something as small as a postage or food scale, and it won't be expensive to buy at all if you don't already have one in the house