Time of day doesn't matter. B-12 and some types of calcium are best on an empty stomach but not worth the risk of forgetting. Just take more B-12 if you want to take the lot with meals. B-12 is cheap. I take them all as a bunch around noon, mainly because they settle better after my breakfast has settled. I took them with breakfast for years.

Vitamins are not like taking a drug. They benefit is a result of weeks of disciplined use as they help the body and brain metabolize energy better and do other important functions.

You could go OCD and break the regimen down into optimum times but I doubt you would be disciplined enough to take them consistently. Most just do not have the time.