Went ring shopping, when do you think he'll propose?

My boyfriend and I have been together for a long time but I was just ready to get engaged last year since we're doing well financially and it seems like the right time for both of us. We finally talked a few weeks ago about being engaged for at least a year to plan a wedding in summer or fall, what size of a wedding, and he said he planned to this year on a special date and wanted it to be a special surprise.

I needed more clarification so later I asked for a more defined timeline rather than "this year". So now I know it'll happen before we leave for vacation with his family in September (He knows I wouldn't want a proposal in front of his family if my family isn't there). We also went ring window shopping to get ideas and get sized. Since then, he hasn't said a word and I'm thinking it is because he doesn't want to lose the surprise element. He somehow always manages to surprise me even after all these years in little ways.

Honestly, talking about it was fun but at the same time I didn't want to learn more because I like the idea of a surprise. At the same time it is making me very anxious and I don't want to keep pressuring him to give me more details if it is a surprise. The only hint I got was a "special date" which I assume is our anniversary in July but other than that I have no clue. Maybe when I graduate with my MBA in May, the trip to San Francisco next month when we go to wine country, I'm not sure. So I have about 4 months of obsessing over when.

I know you all won't have the answer to my question but did you have an idea when your fiance was going to propose without him telling you the date? If I had to put my money on it, I would assume by our anniversary because he's just that "type".