Yes, once you and baby are very comfortable with nanny I love the idea of you "leaving the house" and then sneaking back in upstairs if possible. Maybe the nanny takes the baby out for a walk while baby sees you leave and then you return before they get back from walk. Nanny could always take the baby out for a late/evening walk too to give you a chance to "come home".

I agree not to constantly check in on baby once baby is secure with nanny however I do think you should have regular scheduled check in times after spending time together with nanny for a day or two.
I did this with my son when he was 6 mos to 1 year and it worked well after he was very comfortable with sitter and then we did things the same way every day. She hung out with us, then I went upstairs, and came back down every hour or so, while he was awake. She would take him on a walk in stroller for his naps.

Very, very hard when the baby knows you’re in the house and won’t come to her/him. It’s not separation anxiety, really. Your baby just wants who she knows.

Leave the house. Say goodbye and leave the house. Sneak back in later and don’t pop downstairs for any reason.

My BF just lost her new, highly sought after, nanny because my BF kept popping in. The nanny quit.

I'm sorry OP. This is really hard. As one of the other posters suggested, could you have a few days where it's the both of you so your child feels more comfortable with the nanny?

Also, could your nanny take your baby out of the house first thing so that your baby isn't watching you go upstairs? I realize this doesn't work on a rainy day like today.

Babies also understand more than we give them credit for. When it's time to go upstairs, give your baby a big hug and say "It's my work time right now. I'll miss you so much, but I'll be back downstairs for lunch, or I'll see you at nap, or whatever it is.

Lastly, I would do my best to create a routine and stick to it, to set your baby's expectations. Babies learn super fast, and consistency will help them learn more quickly. I don't think it would be good to constantly be checking on baby when she cries, or I think it'll reinforce that behavior.

Also, if you can schedule it in, have nanny come over for a few days to start where you, nanny and baby hang together. day one 2 hours, you can get up and do things around house all three of you, then nanny sits with you as you feed baby, etc. Day two: Nanny holds baby for a little while you get somethign quick done, you and baby and nanny play on floor together. Day three: You leave nanny and baby alone together for BRIEF periid while you go upstairs, you come back within 10 mins so baby sees you come back.
Then when you are working you come down every hour baby is awake etc

very hard. Maybe leave a shirt that smells like you next to baby. Also, maybe come down every 10 mins to start for the first hour then 20, then 30 and so forth for the first days. It will be a transition NOT a clean break. Long view.

Our wonderful nanny just started and our 9mo DS screams whenever we leave the room. We are working upstairs (covid) so it's hard to make a clean break. Any recommendation on how to smooth the transition from parent care to nanny care, especially when we are still home?