Normally, no, you don't want to go earlier, that will be too soon. Hard to say what this year will bring.
I tried to find something online to help you...there is of course the larch tracker, but that will not be active until it is much closer to the fall season.
https://www.engadin.ch/en/guide/engadin-holiday-resorts/the-golden-autumn-in-the-engadin
Swiss Family Fun has some hikes and photos and states that "mid October to late November" is the best time.
https://swissfamilyfun.com/golden-larches/
I have been to other locations - Davos and Zermatt for the larches and it was in late Oct/early Nov. for both, in different years.
Another suggestion is to look at the official social media pages for tourism in the area and go back to last fall to notice the dates of the posts.