Hello my mommy friends!!!

We have been using the DockATot (placed inside her crib) since my little girl was born! She has sleep so well in it and will sleep all night long!! We absolutely love it but I worry that we are getting close to putting it away!! She will be 5 months old this month. She is starting to learn how to roll on to her belly! How old were you little ones when they stopped using the DockATot and what was the best way to transition to crib mattress?