Don't bother trying to dps if you're a beginner to the healing job.
This is something you think about once you have a really good knowledge of your healing toolkit.

If you're still not confident with what you're doing, read again your healing skills description and make some test, watch some guides, pov...
And then later after that, you can think about dpsing.

But indeed, if you see that no one is taking damages for 10s, if you want to minimize risk but still do something : use your dots.
It'll be a small contribution at low risk, its instant and have a 30s timer.

Don't worry.