Metformin takes a bit longer than a couple of days to start having an impact as far as I know, but it may simply be due to the fact that you have made modifications to your diet (if you have!), and just generally coming to terms with things. Many people experience 'squiffy' vision too, as your blood sugar levels are probably quite high still, and fluctuating. Most people find that things settle down in a week or two, and it's advisable not to get any new glasses until you are absolutely sure that everything has stabilised.
I imagine that, whether you are aware of it or not, you are also under quite a lot of stress with so much to take in. Be patient and things should ease in time, but do see your GP if you are worried 🙂