At 4, I'd let her coaches dictate the pace. As her mom, just make sure she is having fun and getting enough rest and good nutrition. My daughter started at 7, Level 4. She is now 14 and second year Level 10. Most parents will experience some kind of sticker shock at one point or another, either in tuition, days/hours of practice, meet fees, coaches fees, competition leo and workout leo costs, etc. Then there is traveling quite a bit for meets as you get to the higher levels, splitting the household in two because meets may require the whole weekend.
No one can really prepare you because gyms are managed, coached and trained differently. Most parents are "overly" and outwardly anxious and too invested in the sport in the first few years (myself included); largely because (I think) they think their kids are so darn cute (and they are,) and we are impressed that our little suzy went from walking to tumbling and doing things we couldn't do ourselves. Then that wanes and anxiety turns inward as we just hold our breath not just wishing they'd get that skill but merely hoping then don't hurt/injure themselves yet again! At this point, really just enjoy watching your daughter and share in her joy and celebrate her getting any skill she is currently working on.