Just wanted to know when I should start topping? What day or week?
You want to count the nodes and top around the 5th or 6th depending on what you feel like. I do the 5th, weeks won’t matter, it’s all about the progress of your plant. Do you have a pic we could see?
Alternatively there are a lot of YouTube videos on how-to. That said, there is a lot of misinformation on the web as well.
This one is accurate and reliable
Looks like it could use a little more growth but you’ll probably be close