How do you personally approach queenless hive?

I know every beekeeper has their own method. At what point do you intervene with a purchased queen? I have several queen cells and I stopped seeing eggs about a week ago. Now I only have capped brood. I’m guessing my new queen probably has around a week left before she is born and will have a week as a virgin.

Does anyone here just automatically buy a queen if you catch the hive queenless early in order to avoid a gap in the brood cycle? I know they’ll kill a bought queen if there’s a virgin around, but I’m not sure about just queen cells only.