As suggested above. Baby Sensory groups, library rhyme time, swimming class.
Going for a walk whatever the weather.
Getting him weighed.
Meeting friends.
Play nursery rhymes on YouTube to sing to.
My local theatre has a bring your baby comedy sessions once a month.
I sometimes go in the car wash as I’m bored and it gets a job done! Same with food shopping.
Card shopping for the next few months using sling and show him them?
I try to just chat about what I’m doing when getting on with housework and show him stuff to look at or touch.
I look at very simple black and white books with him from the library.
He likes his rattle now. I’ve got a few lentils in a small plastic bottle.
Tummy time.
I also do a circuit of playmat, buggy (lie flat one to sleep), bouncy chair, tummy time, sling, in my arms and repeat! Looking forward to adding jumperoo in the mix! 
Maybe time to take him shopping and get cracking on Christmas presents?! (scraping the barrel!)