Ehh, it'll take them a while to wean completely, you'll want to keep them on crushed pellets more than the adult brine, I'd do bbs in the afternoon crushed pellets at nooning and night to see if they will wean faster that way. I'm taking mine slow because I don't need to rush for anything, but you might want to just skip straight into the 2:1 pellets:bbs stage. You might lose some of the smaller ones from this, but its better than not having the majority weaned by the time you go on vacation.
7 weeks is a good time to start weaning, but I would start with some crushed pellets. They have more nutrition in them than bloodworms....you could definitely try the adult brine too, but make sure you are feeding bbs at the same time so that if they havent got the idea of pellets yet they dont starve.
Right now mine are on Microworms and getting NLS Small fish formula, MW's in the morning and before bed, the NLS around lunch....soon I'm going to make 2/3 meals NLS and then eventually all will be NLS.
My fry are at 7 weeks old now and I was wondering if I could start feeding them other food besides bbs. I can get hold of brine shrimp and frozen blood worms. Will any of these be ok to feed at this stage?