Filming schedules info

I have got all the actors, props and script ready for the filming that will take place on 15th and 16th of January. The actors in my film said they will provide their own costume suited for their role and the location is set up for filming. If I will have to film on different day which may be after the shoot, I will have to make sure the lighting and weather is the same to avoid continuity errors. I planned to shoot on the 7th and 8th of Jan but both actors were unavailable due to revision for their exams, but the new dates will most certainly go to plan.