Well, it depends.
The airfare pricing dynamics can vary based on where you are flying from. If you have very limited options and the flights frequently fill up, then you are less likely to get fare sales and discounts. I suspect Grand Rapids proper has a limited schedule of flights and you likely will be connecting through someplace--Detroit, Milwaukee, Chicago, Atlanta, etc.--depending on what carriers serve your airport. If you can get to one of those busier airports to start your trip, you may have more options and better pricing.
Flights in the middle of the week to and from resort destinations can be less expensive than weekend flights; although if any part of your trip (i.e. Grand Rapids to wherever) is primarily filled by business travelers that might not be the case.
I would suggest that you start looking now at what your options might be and get a sense for pricing, routing options, etc. A site like Expedia or Travelocity is a fine place to start this research, but I would book directly with the airline in most cases. Then, when flights for your dates are available--generally 330 days out for the legacy carriers, closer to the travel dates for SWA and some others--you can see what prices look like and start to see if they fit what you have seen.
Any fare sales, which do happen for summer travel dates, likely will come out next spring. You always can wait for that, but if prices are low and fit your
budget before that it may not pay to wait. Every once in a while there are last-minute deals, but unless your plans are very flexible and you can make changes less than a week out, they aren't of much use. Whatever you do, don't wait until inside of 14 days to book airfare because prices will skyrocket at that point barring any last-minute specials.
Sign up for the email alerts that the airlines serving your airport will send out. That can give you a sense of what their sales look like, when they come out, etc.
With a group of seven another thing to be aware of is that most airlines have a limited number of seats in their lowest prices. As a result, if there are say four seats left and you check on pricing for seven it will price all seven at the higher fare. Some airlines will price four at the lower fare and the rest at the higher fare, but most often you may need to play around to see how many seats are left at bargain rates. Needing that many tickets also may indicate that you should think about booking earlier rather than later.