I think Disney canon was sticking closer to the opening crawl all things considered. it does say Rebels got their "first victory". In legends you had full scale battles and even victories like Kamino well before Toprawa (Legends equivalent to Scarif), canon plays it a bit safer, but there is still a civil war ongoing. Rebels even skirts this with the Alliance not "technically" being behind the liberation of Lothal which is pretty resoundingly a victory.

In Disney canon was have dozens of battles and operations prior to Scarif, Andor was not beholden by Disney canon to not have an Alliance military operation happen in the show. One did not happen because the show was shortened to one arc instead of one season for each year. Plus with what I was suggesting, it does not even have to be a win. Saw did several hits on the Empire, 2 in Rebel Rising, which saw serious violence and collateral damage/massacres. As well as the much cleaner though ultimately only temporarily victorious taking of a facility on Kashyyyk in Jedi Fallen Order.

In canon the time frame is essentially the same as legends, just the scale of results is different. The Alliance is declared 5 BBY, and the civil war begins in earnest 4 BBY. Saw and the Rebels crew even blew up a Star Destroyer in what amounted to a strategic loss for the Rebels, but still a huge number of dead Imperials. That is the kind of operation I am talking about.