Training for Colorado 6K in June--Training Schedule Help

I'm hoping for input on putting together a training regimen to prepare for the USMS 6K in Colorado in June. Also curious if anyone on this forum is signed up for that event? I'm so excited, but I'd prefer not to waste valuable time with an ineffective training plan! My mile time in the pool is around 28 minutes. I've done several 1K - 1 mile triathlon swims and I love the open water but it's going to be two months of pool work before I can get outside. --Kaly from Idaho.