Yes to what everyone said, @David1648, and I will add to be very careful and do a double check. I opened a new listing a few weeks ago just as an overflow for my main listing - a nearly one-shot deal. I blocked the entire calendar by default, as was offered by the system. Then I opened the two days I wanted to be bookable, and all seemed well. That was until I went back into the calendar and found the whole thing open and available via Instant Book. I'm a grizzled veteran of hosting and not easily tricked, but that was a big one. It made me suddenly sympathetic to the plaintive posts of new hosts.
So once you have opened your two weeks, sign out then back in again and check to see that everything is the way you set it.
All the best!