Star vault trade-in

I have 1183 stars. I have already finished the album. I have seen the chart previously posted that someone kindly did, which shows recommendations for each amount of stars and what vault(s) to “buy” or don’t “buy” to get the most dice. I was curious if anyone knows if I can buy the 700 vault and close my app so that I can use those stickers for the next album. Otherwise, I believe my best bet is to buy both the 250 vault and the 450 vault, based on that chart and the amount of dice I would receive.

Also, curious if our community chest will automatically open before the end of the album if I open the app. Advice welcomed!