If they have milk bands, I wouldn't feed them.
Check their milk bands in the evening, your time.
Hopefully by then their mom will have adjusted to her new role.
It is possible you will have to hand feed them kitten formula or infant soy formula or find a surrogate mom with babies around the same age but not yet. Their best chance is with their mom.
You may want to get the things you will need to feed them every 2 hours, 24 hours a day for a few weeks ... or start to look for a surrogate mom (& babies) with a litter near their age just in case. If you do hand feed, remember to gently wipe bottoms with a warm, damp cloth, etc to stimulate them to urinate and have bowel movements after they are fed. If you do hand feed them, they will need to stay with mom as she can (hopefully) take care of them in all the other ways rat moms take care of babies.
You can also put her in a small space with the babies where she can't get away so they can nurse ... but you might want to check with others to see if she is likely to react badly to that.
When you check for milk bands, take some pics to post on here so we can see.
Personally, since they have milk bands, I would give it a bit more time. But I am not an expert.