Congratulations on your new wee baby!
For what it’s worth, the person I bought my baby holland lops from was feeding them a livestock pellet and timothy hay when I bought them (at seven weeks). For pellets, I slowly transitioned them over to Oxbow Essentials Young Rabbit, just as MoveDiagonally recommends. This method went totally smoothly and they love their new pellets.
Regarding the hay, I asked my vet whether my babies needed alfalfa rather than timothy. My baby boy was putting on weight just fine with the pellets and timothy hay, so the vet recommended I just keep him on just that, it’s worked out just fine. He’s happy and healthy (just over three pounds at three months). My baby girl is smaller and wasn’t putting on weight as fast, so, at the vet’s recommendation I started mixing her timothy hay with alfalfa hay, and now she’s putting on weigh nicely (adding over half a pound in a month). Personally, I’d try a mix of timothy and alfalfa hay for your new babies, just to make their transition from alfalfa hay to timothy hay (when they hit adulthood) easier on both of you.
Enjoy your new rabbits!