We're going in April (from the DC area) and I started seriously tracking flight prices right after I booked at 7 months. Based on previous experience I WANTED to use either Hawaiian or Alaska Air. We have equal access (50 minute drive) to 3 major airports so we have more choices than most (although we prefer BWI as parking is easier & cheaper). We've been to Hawai'i 5 or 6 times before and I know you really have to watch the total flight duration times because connecting flights can kill the value of the price. I was NOT happy with any of the combinations that I could put together on either Alaska or Hawaiian compared to the pricing. I tried mixing airlines (but keeping departing & returning same airports). They were both priced very high and the flight durations were often 15-17 hours one way. I know the trip can be done in 12-13 hours so that was a big consideration for me too. I really wanted to avoid it taking any longer than necessary to get there.
This is a budget trip so my other thing was that we were planning to book this trip entirely with credit card miles so I needed the total cost to be under a certain amount and we can't afford to upgrade to the "comfort plus" seats.

We have a Capital One credit card and they have a travel portion on the website that I ultimately ended up using to book when they hit a price and flight combo that I was happy with. They had a flight price prediction model that told me to wait to book. I set up a fare alert to watch on both them and Kayak. We ended up booking on Delta in the "main cabin" seating (you have to watch each airline on what cabin category you're booking too or you may not be allowed carry-on bags or seat selections or changes after booking). I was able to snag $708 pp which I was thrilled with. There were cheaper options (longer flight durations and "basic economy" which meant no pre-selected seats so I knew we'd end up in the middle of the middle seating and potentially split up). ONE WEEK after we booked Delta made a big change to our return flight and cut our transfer time in Detroit down to 33 mintues which I was not comfortable with as it's under the airport recommended transfer time. So I called Delta directly and they were willing to move us to a different flight at no cost since they made a change we were unhappy with (a more expensive flight with an even better connection time / flight duration). So now we still have enough miles left in our Cap One account to cover our rental car for the week.
If the flight cost is a big concern for you then you definitely need to be open to considering other airlines. Hawaiian is a great airline but at what cost? They're still running higher than Delta & United when I look and compare them to what we booked (and the times are worse). SET UP SOME FARE ALERTS and get familiar with your prices - don't rush to book your air because you still have plenty of time!!!
(TIP: book a rental car thru
DiscountHawaiiCarRental.com - it's got free cancelation and pay later. We've used them before. I just yesterday was able to find a lower price and I rebooked our rental for nearly $100 less than what I originally booked it for.) I will eventually turn it over to Cap One miles...