Like Joe said, there is no problem with changing feeding days at anytime. In the wild they eat whenever they feel like it. What I wanted to add is, you are asking about upping from one pinky to two pinkies so I am assuming you are feeding one pinky at this time. With baby snakes that are eating one pinky a meal, I would suggest feeding every 5 days instead of every 7. When they move up to two pinks they can go every 7 days. This is just a suggestion.
And no, there should be no reason to feed more often before and upping in size or quantity of food. What you need to do is make sure the snake can handle the upped amount, that is what's important. If after the snake eats its food the prey item leaves hardly a noticeable lump in the belly, then it is definitely time to up the food. If the prey item is still leaving a very noticeable lump then it is best to wait. Too little food and the snake will not grow well but too much food and the snake could very well regurge.
Good luck with all.
Well, IF you really wanted to learn all you need to know about what you are doing, you would be willing to read through ALL the information you could get your hands on. And what better way then the easy access of a forum where you can read and copy and look things over without leaving your house. How easy would you like it?
I read EVERYTHING on all the forums when I first got my snakes. I bought the books and read them. THAT is the way to learn, not going for the "quick" and easy answers. I have to say, that is a little offensive for you to say that you are upset because someone doesn't answer your question right away and that sometimes you are told to look for the answers. The people you are ASKING to give you the answers are the people who have taken the time to study their hobby and read and do hands on learing, and then you want them also to give you the quick answers that they have written multiple times already. I have no problem giving answers when I can, as I did above, but am offended to have people want answers without putting any effort into it. This takes our time to write these out and we also had to spend the time studying and learning, remember that.