Well you're about to do one of the hardest tasks any human can do, which is raise a child. It takes a ton a patience, care, and work to do it right.

You're company will hopefully be tuned into this and be reasonable and show you some grace through a life changing experience. You also need to be kind to yourself through the journey. You will have to make adjustments, but it will be worth it.

As for imposter syndrome, everyone puts their pants on one leg at a time. Just keep learning and doing your best and you'll be fine. The fact you're asking this question at all is a good sign.

Congratulations!