As I understand it - divs will be constant until the next difficulty change (mid-next week I believe). Then, they should be constant until the next difficulty change (2 weeks later)
Keep in mind the difficulty change is defined in the code as every 2016 blocks, which means that in a time of rapidly rising difficulty, the next difficulty shift can happen quicker than 14 days, because the blocks are being solved faster than every 10 minutes. For example, I believe the most recent difficulty jump of 28% happened in a time period a few hours shy of 12 days.