The SBIR program has 11 participating agencies as of July 2017. Each agency will set their own timelines for their SBIR solication, application, review and granting schedule. You will need to do research to find out what the timeline is for the agencies that are relevant to you.
For example, here are the timelines for some of the top funding agencies:
- The Department of Defense has 3 application deadlines in 2017 for 3 tranches of proposals: February, June and October.
- The National Science Foundation has 2 application deadlines in 2017: March, and October.
- The National Institute of Health has 3 application deadlines in 2017: March, July, and September or December.
- The Department of Energy has 2 application deadlines in 2017: February, and October.
- ... etc