How often do Porter fares fluctuate?

I’ve never flown Porter so I’m not sure when to book. I’m looking at booking a one way flight from Winnipeg to Ottawa on Aug 27, which is a bit high right now at $234. So I guess I’m basically deciding whether it makes sense to book at that price with that current 20% promo or wait to see if it comes down further later in July. Any thoughts on this are appreciated!