When does a guy propose a girl?

Answer 1

When they've gotten to know each other, and the both feel they could grow old together.

(Usually minimal of 1 year, that's what it takes to get past puppydog-honeymoon dating phase and start opening up to each other with all their little quirks)

Answer 2

A guy may propose to a girl when he feels ready to commit to a serious relationship with her and wants to symbolize their love and dedication through marriage. This decision is based on their emotional connection, mutual respect, and readiness to take the relationship to the next level.