@Bob951 You can manually unblock the dates in your calendar, just the same way that you blocked them. But if you don't want someone else to book first, you'll have to leave Instant Book off and, decline any requests that overlap with those dates. (I see no point in doing this, but if you're particularly attached to hosting this guest rather than one who already has the funds, it's your call).
Also, you don't have guests make a "deposit," that's not a thing. Airbnb offers the option of splitting the payment, but this is clearly visible to guests during the booking process and it's not your job to counsel them on it. Just tell the guest to hit "Reserve" when they're ready, and Airbnb will take it from there. It's one of the few services you get for your service fee, so why get all up in the middle of it?