My FIL and his wife got married 1 1/2 weeks before us. One of my best friends got engaged 2 days after we did and is getting married next month. I am her matron of honor. One of my other best friends got engaged in May and will be getting married in January. Not to mention, about 6 of us got engaged at the same time at work.
It was a little crazy planning our wedding while still trying to be there for everyone else during this special time. Although I know the situation is a little different from yours, I never felt like my time wasn't special because other people I loved were plannning their weddings too. Actually, it turned out to be wonderful because I got an instant bridal support group. Bottom line your day is going to be incredible because you are marrying the love of your life at the right time in your life. Nothing else will matter.
Like the other girls said....just by pass the waiting issue by footing the bill yourselves. And regarding making sure everyone has their share of attention, don't worry. I'm sure your family and friends have more than enough love to go around. Good Luck!