Typically fares are set after 2:00 am and vary from day to day.... It is done on a complex equation, so if you try one evening and cannot find a low fare, it may be available in the morning.
Typically the lowest fare can be found with a minimum of 3 weeks before the travel dates, but it all depends on destination, air line, seats sold on the flight, time of the day, and ... I have known to buy an air fare 6 months in advance when I found a 50% sale from typical rates as well as 2 weeks in advance.
Bottom line, the fare could go back to $177. Keep an eye and buy it when you think that you are getting a good price. You never know if it will go back to $177 or if $310 is the best between now and your travel time.