My daughter did a mommy and me and rec classes to age 5. She was at a no pressure rec only gym that we loved and still keep in contact with the owner. The summer before kindergarten she had more skills than they offered. So we moved to the gym my daughter is at now. They immediately put her in level 1 for her kg year. Level 1 practiced 2 days a week for an hour and a half. She then skipped level 2 and was in level 3 for 1st grade. My daughter's gym has pretty low hours for their pre team and levels 3 and 4. So I only worried about it being too much every now and then. Let's face it, as a mom I've worried about each step being too much...
Many of her teammates didn't start level 3 until 3rd or 4th grade. It was more based on when they were ready skill wise and had the interest of doing so.
So if I were you I'd would base it on her interest level, her skills, if she is looking bored, and if there is a class that offers her appropriate skills with a similar age group.
At her age, and really any age, it should be all about fun for as long as possible. Eventually the gymnasts have to have days where they put in more work than the fun they get out of it. But if your daughter wants to stay in long term she needs to find her passion in it before anything else.
And always feel free to ask the coaches what they mean by potential, what the next steps are, what the options (rec, Xcel, JO) are at her gym, etc. If you feel push back from the coaches just for asking those questions it should be a red flag.