Can I change my birth plan last minute?

You could, but it's better not to, so you can have ample time to discuss with your gynae if what you want is feasible and agreeable by your gynae. There are certain things which your gynae may not practice such as delayed cord clamping or labour in water, for example. It's better to draft out a good plan and stick to it rather than changing it at the last minute.

Why not? It's your life and your baby. You definitely have the right to choose what you want. Hopefully that does not pose too much of a problem for your husband or family.

thanks