well if your running out between the time you dose and the next time you will need to up it. as long as you keep remembering to do it well if your doing EI it shouldnt madder if it was morning night day or when even as long as it gets done. like always i could be wrong.
I still say, that, while slight variations in time don't matter, it's a best practice to shoot for the same part of the day, whether it be morning, night, midday....whenever, just keep it consistant...again, best practice.