I want to buy my girlfriend an engagement ring

My girlfriend and I have been dating for 10 months and I plan to propose at Christmas. I have been saving for the past four months and I almost have enough money to make a nice down payment. The jewelry store in the shopping mall will finance most of the cost if I have $1,000 to put down. I already picked out the band and the setting and the center stone diamond. My girlfriend doesn’t suspect a thing, even though we have been talking a lot about commitment. She doesn’t think I’m the type of guy to surprise someone with an expensive engagement ring. I never thought I was that guy either, but she makes me feel like I can fly. I’ve been working a lot of overtime lately and we haven’t seen each other much this week. I spent Monday and Tuesday working until dark on a geothermal heat pump installation project. On Wednesday, I went to work early so I could finish the geothermal heat pump installation job and get started on another installation job before lunch time. On Thursday, my girlfriend and I had dinner and she was upset that I was spending a lot of time at work. I made an excuse about guys taking vacation during the holidays. I told her that we were really busy with air purifier maintenance and air filtration installation jobs. I promised that I would take some time off after the holidays. I’m so close to buying the ring. I just need her to hold on for a few more weeks.
a/c set up