The audience most likely to turn up is the one already nearby and looking for something to do. They probably do not follow you. Reaching them is less about posting more often and more about being findable by someone who does not know your name.
People rarely search for an entertainer they have not heard of. They search for a place, a night, or a kind of music. That means the details around your gig do more work than the gig title:
A single announcement the day you confirm is not enough, and posting daily wears people out. A reasonable rhythm: announce when it is confirmed, remind roughly a week out, and remind again on the day. Each one should carry something slightly different — the announcement gives the facts, the reminder gives a reason.
The venue has an audience that already goes to that room. They are far more use to you than another post to your own followers. Make it easy for them:
The people who go to that room every week are a better audience for your gig than most of your own followers, because they have already decided they like going there.
A past gig still shows that you play, and where. Leaving your history visible builds a picture over time of someone who works regularly — which is exactly what someone deciding whether to book you is looking for.
Practically: list the date as soon as it is confirmed rather than the week before. It becomes findable the moment it exists, and anyone following you is told. To see how it is done well, browse what is on near you and look at the gigs that tell you everything at a glance.