Have the conversations you need to have well in advance so you don’t let on what’s coming. You need to know a lot about your girlfriend before making the perfect proposal. You probably do, but some of the details may be harder to know. Like her ring size, her taste in ring, and bigger things like if she would even say yes.
These are questions that if you ask all of it close to the time your going to propose she will figure out what’s up and you will miss out on it being a surprise. Well in advance, find these things out. Find out ring size, know what her taste in rings are, if she wants something extravagant or not. Know how to make it special for her. And know if she wants to get married and would say yes to you.
Early on start figuring this stuff out. The sooner the better, cause she will catch on less the further from the day it is. If it’s nowhere near time to get married you can straight up ask her a lot of these questions but, close to the big day and it will ruin the surprise so you will need to be extra sneaky.
Either way, find out what you need to know without her knowing why.