I suppose you want to have certain knowledge where you are able to understand and code some basic
actions and control for your robot such that it meets your requirement for the time being as you have
to get something built up quickly for your project, later to which you could build up on the basics you
would have gathered.
Being specific to Turtlebot 3, you can try the ROS development studio and its tutorials which give you a fair idea to get started with (coding and code manipulation) dealing with basic movement to creating launch files and nodes quickly.
Also, there are many tutorials from The Construct concerning ROS dev studio that give a clear idea to how it's done.
Meanwhile, you could refer this which is pretty good enough compared to bulky ROS books. Besides, instead of paying for tutorials, the same are available on Youtube.
On the other hand, with this material you can petty much decide which would suit your feasibility such as using Python or C++ in ROS.
I'd say, first work on learning to program and using Linux and once you're comfortable with that then you should start working with ROS. If you try to do it all at once you're going to have a really hard time.
Yea i worked on some tutorials posted on the turtlebot3 website and i got SLAM and stuff working
That's great. But, if you're new to programming then you're going to have a lot of trouble (I've seen it many times both here and IRL). So, look for good resources for the programming language that you're going to use (e.g., Python, C++) and for Ubuntu/Linux. Then learning ROS will be easier.
What videos? What don't you understand? Being specific goes a long way.
I took a course on C++ a while back but we mainly used to analyze the codes and see what they did, for videos I was looking for how to make a package and try to launch the package and if I can modify existing packages. Also how to use codes that are already on Github.
Then you should definitely check out the tutorials on the wiki that @JAWDAY linked to in their answer for text-based tutorials (they're the only "official" tutorials that I'm aware of). As for videos, I can't vouch for any.
Will do, Thanks for your help. My prof told me the ROS forums are pretty active and a great community.