There’s no time like the present to make things better.
Refactoring should be a regular part of your development habit. Write tests, develop the code, and refactor to make it better. Then the cycle repeats! Over and over, you add more tests, add more code, and refactor to make the whole thing better. Always refactor, every day.
Each time you refactor, you have a chance to make the code just a bit more awesome. Simplify. Make it more DRY. Apply the SOLID principles. Improve the code. Make it more clean.
Software engineering a wonderful profession. Unlike physical engineering, we can replace components and make improvements pretty easily. If you build a bad bridge, it becomes a year-long project to replace it. If you have a bad subroutine, it can be fixed in under a day.
So get to it.