So let's say you sin on Tuesday and Confession is on Friday

So when you're not in the state of grace, after you committed a serious sin and before you've gone to Confession, you are cut off from sanctifying grace. But you can't be cut off from all grace, and I'll tell you why. Every good you do is prompted by grace, by actual grace. So, any time when you're not in the state of grace and you do something good (like go to Confession), it is because you are prompted by actual grace.

And you can pray for actual grace to help you go to Confession, or to reform in whichever way, whenever you want. And you can pray to the Saints for whatever intentions. God can't send grace that will get you into heaven, but you can still send good stuff his direction. And in the meantime, he will supply you with plenty of actual grace to get done what you need to get done.

Meanwhile, you can explore the possibilities of purely human discipline. No one can avoid sin completely without sanctifying grace (even with it, it's tough enough). But until you get to Confession, you can be like a good pagan (there's no salvation outside the Church; there's no salvation out of the state of grace). Be like a good pagan and discipline yourself better to avoid sin (using actual grace), and also get that actual grace you need to get to Confession. And then you're all better.