My advice is that if you have limited time, apart from using the advice of AnimeKing314, focus on short things. For example: Today I want to learn how to make the MC move between rooms (use example images for the code).
Another day you can switch and do renders to get familiar with HS.
And you switch back and forth until you get used to work with both (I remember at the beginning that if one day I worked on code and the next day on renders, I forgot how to do the code hahaha).
But I insist! You have to see your possibilities in both things, don't try to "promise" yourself that you will do something that later you won't be able to achieve because of lack of knowledge, go at your own pace.
Go step by step and if you have to redo code later, it doesn't matter, nobody has to replay the game but you.
At the coding level it's hard to say where you can save time other than learning how to use the classes. Our code is like our "house", in the end you arrange it as you think is best.
Set short goals and focus on learning them before moving on to the next one. Go and put it all together little by little and see where it fails, because it will!
Having limited time, you can also plan to make short versions of your game when you learn everything, this way you have much more control of the code and the bugs.
My last coding tip!
Learn to differentiate between show image, hide image and scene image, the attributes when declaring images, and those things related to images. This way you can get the most out of what AnimeKing314 advises you.
