Huge +1 to this plan. Nothing compels one to to learn to swim like being thrown into a shark tank.
For shrinking the overall size of the endeavor, a lot of conferences / meetups have a lightning talk section so rather than filling in 45-60 min of time, you've only got to do about 5 minutes, usually with a hard cut off. It's a great way to get your feet wet.
+1, lightning talks are amazing as a speaking opportunity. They're drastically less scary than a 40 minute talk, so it's easy to give it a go with a simple talk without much prep, and as you gain experience they're an amazing place to practice honing more complex topics down to their essential essence.
For shrinking the overall size of the endeavor, a lot of conferences / meetups have a lightning talk section so rather than filling in 45-60 min of time, you've only got to do about 5 minutes, usually with a hard cut off. It's a great way to get your feet wet.