[run] before {sb} (can|could) walk

to make an attempt to do something difficult without having the requirements or means to do so

The origin of the idiom "run before someone can walk" is not very well documented, but it is used to caution against trying to do something beyond one's current level of skill or understanding. This phrase implies that it is important to learn and practice the fundamentals before attempting more advanced tasks.

The important thing about cooking is not to try and run before you can walk.
They tried to run before they could walk.They made it too complicated.
She wanted to tackle the most challenging tasks at work right away, but her manager advised her not to run before she can walk and focus on learning the basics first.
In his eagerness to become a professional chef, he tried to prepare complex dishes without mastering the basics of cooking.He was running before he could walk in the kitchen.
Starting a business without understanding the industry and market is like running before you can walk; it often leads to failure.