Changing times

Jessica
I currently take the pill at night. Due to changes in my schedule it would be a lot more convenient for me to take it in the morning. I know that the effectiveness decreases when you don't take it at the same time. So my question is, how exactly do I go about switching when I take it? Please be specific with your advice...
-when's the best day to switch? 
-do I switch times gradually or all at once? 
So many questions, but those are a couple 
Thanks for any help!