Sounds like a great idea!
Setting up a meet up group is always a great way to expand your social network and make more friends.
One thing to be sure of is knowing there's enough people in or near your town or city to make it work. In this case its whether there's enough people with AS living locally. That will really depend where you live. I would personally recommend making the group also open to NT's who are keen to socialise and support people with AS, as I think this will help it flow better socially.
Best to get at least 6 or so people together first, and then just organise a first meet up in a local pub or cafe. See what people want from the group, and if anyone is keen to help run it. There should be plenty of facebook community pages and local pages you can use to promote the group and ask people to join.
The main thing is to start small, just collect the people who are interested, arrange a small meet-up, take it from there and let it grow.
All the best!