Hatch door on release cage questions

[Daisy21]

I apologize bc I don't really know if this is the right place to post... Hopefully my post is visible.

Last September we brought in a baby squirrel after not being able to reunite.. I had concerns overwintering her. I was also 6months pregnant at the time! Anyone who read my post will be happy to hear Daisy the squirrel is doing great! Thanks to all the experts, posts I read on this page, and advice I was given, we survived winter.. not only did we survive but I even kept my sanity thru caring for a squirrel AND a NEWBORN! Along w our 2 dogs and 3 indoor cats.. phew! (Daisy never had contact with the other animals).

So to my question.. Daisy was in her release cage outside for 4 weeks. I opened the little hatch door one week ago on 5/20. She stuck close by for the first 3 days before venturing out into the woods on the 4th day. I was beyond happy!! Every night she has come back to the cage to sleep in her squirrel box. So I close her hatch at dark and open it again in the morning.

QUESTION: When can leave the hatch door open for her to come and go as she pleases.. it is 4in x 4in opening and she has a squirrel box she sleeps in. I purchased it from Exotic Nutrition so I assume its predator proof?? Pics of her cage below.

Thanks in advance