The following two arguments are both plausible approaches to accomplishing something:
1) Just start working, and figure it out along the way.
2) Make a plan, and work on the important things.
There are times when "just start" works best, and there are times when "make a plan" works best.
But I'd be willing to bet that in the majority of cases, "just start" delivers better results than "make a plan."
We all have a natural tendency to procrastinate, and "make a plan" feeds into it.
How many people have you known who make careful plans about how they're going to start going to the gym or change their diet to lose weight? And how many of those people succeeded?
It's far too easy to look up yet another article on the internet, or to spend time researching which tool to buy.
If you can clearly articulate why making a plan would be better, and it's a airtight case, go ahead. But make sure you set a time limit on your planning.
But in most cases, you should just start.