Waiting for a plan to come together? You're waiting for it to coalesce. Coalesce is when different elements of something join together and become one.
In coalesce, you see co-, which should tell you the word means "together." The other half of the word comes from alescere, a Latin verb meaning "to grow up." So if you are trying to start up a photography club at school, once you have an advisor, some interested students and support from the administration, things will be coalescing or growing together. Another way to remember that? An adolescent is one who is growing. A lot!