When DS turned one I started taking him to a parent and child playgroup. It's 2hours one morning a week and free. I didn't sign up for any of the 8-10 week long "programs" at that age because they were always at inconvenient times around naps and meals and I didn't want to commit to a place and take it from someone else (the good ones in our city are limited to 8-12 children and spots go quickly) and I didn't want to pay for something and then end up only going to 3/10 classes due to naps or meals (a lot of them seem to be from 330pm - 530 pm which really seems strange to me- you get home at 6pm and have to make and feed dinner, get LO into bed all in an hour, that's a rush for me!)
Also I found that from about 14/15-18/19 months, going through the 2-1 switch led to a lot of uncertainty with what time nap would be so that was another reason I didn't want to sign up for anything and commit/pay for it. As it was with my 930-1130 playgroup we only made it half of the time.
This spring when DS was about 19 or 20 months I started going to one of the 330-530 playgroups (3.50 Euro a session but you don't sign up and commit, you just pay on the days you go) and it is a huge rush to get home and have dinner but we manage it most weeks now though I probably won't take him in winter when it will be a longer trip home (I don't drive here so it's bike or bus).
I did take him to lots of activities but just on my own - we have an indoor soft play center (though it's not a very good one esp compared to some I have seen in England!) and a really good water park (like big tube slides, lazy river, wave pool, kids water garden, etc) and at least then I could come and go on my own time but I still felt he got just as much out of it as he would have if it had been an organised class...there would be other kids there and he could choose to interact or not (though there is not really that much interaction until closer to 2yo and even then it is parallel play and not so much "playing together") and still see other kids playing, and so on. I didn't meet many moms that way (made one good friend that I met at the swimming pool once) but that's also because I'm an expat here and don't speak the language