Pre-Engagement Or Engagement

I am 57-1/2 years old and about to retire after 31 years of working. My girlfriend is 56-1/2 years old and is looking for a new job. We are very much in love and have talked about the possibility of getting married and both seem agreeable at some time in the future. She is the sweetest, kindest, most beautiful woman I have ever known. That is when both her and my situation are settled and we can go ahead with that next step. In the mean time I was thinking of getting her a pre-engagement ring until the time seems more proper to buy her a real engagement ring. We live 35 miles apart and see each other once during the week and on weekends. We have been together for 7 months. Should I be thinking engagement or pre-engagement given these conditions? I want her to know that I am hers alone and that all my heart and love belongs to her.

Ed