Any other T1 on metformin? How fast did it kick in?

I just started a 500mg dose last night. I'm curious what you noticed first or how fast it went to work. How soon after did you have to modify your insulin doses? Did you start with basal or bolus first?

So far I seem to be lucky with no side effects. My doctor said it could take weeks to notice anything but my levels seem to be more stable than usual. Less up and down, more flats. Might be coincidence but this is very unusual.