So every time I have made any progress with a parser, that's the 2nd part of your compiler / interpreter, I have made sure that I am reasonably drunk. Your going to want to drink atleast 2 beers before attempting to write a language, this also prevents the feeling of "why should I write this thing" because yes we have already got several thousand other languages and only 1% actually make it to daily usage.
Know your goals, my language takes two popular languages and smooshes them together, Jess is designed to make CSS the sole owner of styling code including JavaScript.
Make sure you have time, this is not going to be easy. You will learn a tone about your daily language but it might mean learning some new languages too. So far I have picked up Rust, Zig (♥️), C++, C and AssemblyScript, all for a Wasm backend, I am trialing them all not because I like one over another, I am trying to measure how productive I could be in an hour, what are the pros and cons of my choice.
What does your language syntax look like 👽👾, should it fit the same style developers are accustomed too.
Be prepared to forget about good coding standards, just get it done and tested then back track.
Merry Christmas!