I went through this exact question when I was looking at mature dating sites, so here is what I found.
After a few weeks on it the only question left was whether the safety tooling is more than a checkbox.
Most of my useful conversations on it started midweek, which says more about how discreet the notifications are than about timing.
If you can only manage a few evenings a week, whether it thins out after the first week matters more than raw volume on the site.
I would give an older membership the opposite advice about mature dating sites, mainly on how precise the filters really are.
Anyone tried mature dating sites on a smaller platform and got a different result?