TLDR: Which social media platforms do you use, what do you post and when in relation to your events you shoot.
For me, I mainly shoot supermoto(think dirt bikes on street tires, that race on gokart tracks with usually a small dirt section) and the race season is from March-October, one race per month. I'm trying to find more gigs to go to (paid or not) so I have quite a bit of downtime in the offseason and a few weeks before each race.
A week before the race, on my facebook page I usually post highlights from the track that I've taken in the past and try to hype up the event. I usually tag each racer that I post(has 1-3 racers in one photo) to drive engagement and also tag the racing org and the track(if they have a facebook page). I think the tagging helps get engagement because the person I tag sees the post(if they liked my page, which they usually have) and also the racer's friends see it if they comment/like.
The day of the race I go out and shoot. I try to post a picture of the track with all the people there at the start as I "check in". If I get a really good shot throughout the races, I'll copy it to my phone, use a program to apply my watermark and post it to my page throughout the day. That process I've gotten down to about 3 minutes done between a race. Usually gets racers that saw it posted online to approach me and ask if I got any good ones of them and sometimes gets me a sale.
After the race I'll go thru and sort photos, and if I find another good shot, I'll post it on facebook, tag the racer/race organization/track. Once I start to get a backlog of pictures(I try to limit to one post every 2 hours) I'll start to schedule the posts out. I'll find a few photos the night after the race and I'll schedule those out to be posted throughout the week.