You must "sharpen the saw".
This takes many forms including adequate learning / training for self improvement as well as investment in your tooling that will pay dividends on delivering faster or with higher throughput.
These are second and third system effects that require intention to monitor or measure but the effect is real.
There’s so much stuff that feels important and valuable, but so little of it really cannot wait until after your wheels are off the ground.
When you read postmortems of startups that didn't get enough customers, often it’s this stuff that actually went wrong. Too much time spent on other stuff than “build something” and “that people want”.
To my experience, it’s difficult to resist all that good advice that’s all over the internet, books, accelerator programs and the like, and saving it all for later. People will tell you “you should get $PETPEEVE right from the start” for every imaginable pet peeve (all the way from legal stuff to unit tests to SEO) and they’ll be very convincing. Trying to resist this is not reductionist, it’s super hard.
Learning is always encouraged, but you should be learning to solve the problems you're about to face. Learning to solve problems which aren't going to be obstacles in the near or mid future isn't helping you in your immediate circumstances. Sometimes the immediate circumstances aren't much of a concern, but when they are, you need to be sure you're learning with that in mind.