Have any of you started your 2-3 year old in dance (or gymnastics or another class) halfway through the year?

I am thinking of enrolling LO in a dance class, but all the ones I am finding began back in August. They have told me they add kids to the class year round, but I am just wondering if it is the best idea to jump in when the other kids have been going for longer? Then again, at 2 years old, I'm not sure how much it matters? It's not like they are memorizing choreography at this age.