Question about premature puppies

Last saturday a litter of puppies were born prematurely, 7/23 was suppose to be their earliest possible birth date. Since monday I've been working with them as the mother is a hot mess to say the least and isn't producing nearly enough milk despite medication that's supposed to increase milk production. I've been tube feeding and supplying sub q fluids. I am very new to this and I have just been helping a breeder and while I believe I've got the general care down I am curious about their development. Theyve been putting on weight and while still small I believe they're headed in the right direction however I know puppies open their eyes in the 1-2 week range, tomorrow technically being their 1 week mark should I be looking for their eyes opening? or since they were born prematurely will it take 3-4 weeks? I'm sorry if this is a really dumb question I'm very new to the world of puppies and I am pretty much learning as I go, this has been a rough introduction to the world but it's become a very valuable learning experience for me. And just as a note I am not doing this alone I am being guided by the breeder and she is doing a fair amount of the work too, it's just during the day when shes busy with a million other things am I taking care of the pups primarily but I can always go to her if something's up. another note I started working with the breeder prior to the birth of the litter, I was previously learning the ropes of the basic care and cleaning and giving vaccines and microchips and etc with the older puppies and how to care for the moms and make sure they're getting what they need so this was very much a surprise to me but I believe it has been going well because the puppies are getting stronger and growing considerably (I can upload pictures if interested)