With down stairs growth I mean your junk grows on T. This usually happens within the first few months.
When periods stop is very hard to say because it varies a lot between individuals. Mine stopped after 2-3 months, which seems pretty standard. Others never have a visit from aunt flo after starting, while some go on for half a year before it stops.
Whether being on gel or on injections influences how quickly your periods stop can not be dissociated from individual variations, and is thus hard to tell.
Gel is always more consistent. You do spike your t levels every day, but only minorly so. Nebido still gives a peak at the start of the injection. Look at this graph for example.

The Enanthate 250 (which is like sustanon) is the grey line and the Nebido (also known as Undecanoate) is the red line. You can clearly see that nebido still spikes.
Compare that to this graph:

Here gel and sustanon are compared. I apologize for the different T units used in the graphs, but you get the idea. You can clearly see how stable the patch/gel levels are compared to the sustanon and to a lesser extend the nebido injection.