I swear things like these make very simple tasks harder than they need to be. I would assume you would want to go for 30 minutes after the box reaches 250. I just line a baking sheet with parchmant paper, put the weed on top, then fold the parchment paper over it and stick in in the oven, and I've never had any issues. BTW, it's best to chop or grind buds up before you decarb the plant matter.