Hi you!
Glad to see you kept the dress down. The topping can happen at different nodes, depending on your style.
If you were training your plants with the Quadline method then you would top everything above the fourth node. If you were growing out a photoperiod with a long veg time then you can top much higher; 6th, 7th, or more above on the nodes.
Autos are different. They depend on the growth rate. There is loosely followed rule that if you are going to top an auto you have to do it within the first 21 days. This is simply because after 21 days an auto could go into flower at any time.
If you are within that 21 day window, and your auto has at least 5 nodes of good growth, then you can top the fifth node. Autos can be hit and miss on topping, so it's a feel thing based on how well the plant is growing.
Whatever you do, when topping leave some stem. If you top too close to the node base then this puts a lot of stress on the 'V' part where the branches join. Too much weight and you risk snapping a leg. Leave as much stem as you can.
Hope that helps.