TDD means that you write tests first, see them fail, write the code, see the tests pass. Writing the code first and then the tests is not TDD. I didn't find much value in tests first, especially because sometimes I really dont don't have any idea of what tests to write and I have to sketch some code anyway. I tend to write some code, then its tests and use them to debug my code. I save the time spent to write some tests that will be irrelevant to the code I eventually end up writing. In very few cases, let's say twice per year, I have to solve very clear algorithmic problems with very well defined inputs and outputs. Example: process the elements of an array and return another array. Then I write the tests first.

Anyway, tests first or tests later both are good. No tests is a nightmare as a couple of projects I've just inherited are reminding me today.

Edit: typoes