Welcome to the community. We are glad you are here.
The Community release cycle can be hard to predict. The driver is less about the calendar and more about when we feel like we have something worth releasing.
We will do a fourth release for Community soon. It will be 4.0.d and will likely drop simultaneously with the Enterprise 4.0 release.
It is also highly likely that this will be the "final" release of community 4.0. The next release of Community would likely be the first release for 4.1. If we follow the same pattern we've been following lately, it would be 4.1.a. I don't have a feel for when that might happen.
Obviously, all of this is subject to change, but that's what it looks like right now.
In general, we do one major release per year and point releases once a quarter.