A glider pregnancy lasts 16 days. When the joeys are born they are only a bit larger than a grain of rice when they crawl to mom's pouch to attach to a nipple and complete its development.
Joeys may not be produced every time the gliders mate.
It can take several months before a joey is large enough for you to see a lump or two in mom's pouch.
While you are waiting you may want to read this web site:
http://www.suzsugargliders.com/educationalarticles.htm