When I had Glic added to my Metformin I saw the benefits within the first week. The downside is the risk of hypos, and this is a very real risk for you especially if you do exercise (I don't!). I now never go anywhere without glucotabs and a muesli bar, and always test before driving, and stop every two hours to retest. Fortunately I'm quite hypo aware... but when I start "going off" it still takes me slightly by surprise, hence the necessary discipline of carrying glucose and testing.