It is normal for the puppies eyes to open at different times.
I like to wipe the puppy eyes with a wet q-tip every morning starting around 12 days of age. It help. Be very gentle and put to much water on the q-tips to really rinse the eyes truly.
If they still have their eyes close at 30 days, I would take them to the vet to be on the safe way.
Don't try to force the eyes to open.
I think they should open soon and that everything is ok right now so don't worry to much.