Firstly, welcome to the Construct community. It's a wonderful tool and to be honest 95% of the knowledge you will learn on older tutorials for C2 has crossover for C3 as well. So don't be too worried. Read and watch as many videos and tutorials as you can. Construct has an amazing workflow and the coding is very intuitive.
I was in a similar situation to you not so long ago. I bought Construct 2, than within a few months later Construct 3 came out and I jumped on it within the first week of it being released. I did this mostly because I enjoy the whole visual scripting and want construct and Scirra to succeed and am happy to financially support Construct 3 even though currently I am using construct 2 more often.
For me, I use both C2, and C3 that is because I was targeting an older version of Android. If you want to release your game for older versions such at 4.0, and 4.2 etc then I found construct 2’s export easier for me. However, these versions of Android make up a tiny fraction of the market. So it was a more specific need of mine. Due to my only Android phone being ancient and running on 4.2. Construct 3 exports to Android 5.0 and above.
If you already know you will export to 5.0+ this won't be an issue at all for you, as older versions add a lot of overhead, memory footprint and download size.
Another advantage of C3 is the build system. This is coming along nicely. I hope eventually it will even have key signing your apks and will cut my entire need for Adobe’s Phonegap build service.
Also if you have already started your project in C2, it is fairly easy to bring it into C3 later if you find a specific reason or need one of the new behaviours such as the Set color. Assuming any 3rd party plugins you used in your C2 project, also work in C3.
It is much much harder to do it the other way around. I recreated my entire game from C3, down into C2 basically having both projects open. Creating the same sprites, names and layers, and it allowed some copy/pasting of the event sheet over, but it was a slow process and I had to manually check I made no mistakes.
Anyway, good luck with your journey into Construct. There is a lot of amazing tutorials on here, Youtube etc. One of the best parts of Construct is its community. I have been lurking for 100s of days reading as many of them as I could.