This is probably the most common question that we get. With Speed District, you are not locked into a group. We recommend starting in a lower group, then after two sessions, feel free to switch to a group higher. We do not recommend starting in the faster group then dropping down to a slower group.
Also, your lap times do not dictate which group you should be in. The advanced group is open passing, which means people can pass you at any point. We would recommend reading this article regarding run groups.