Cathy, You can plant pumpkins from June on, it just depends on when you want them to mature. Just determine when you want them and check on their growing time and make a judgement. It has always been my experience that they mature earlier than stated on packages, so allow a week or 2 leaway.
Happy Harvest,
lisa

Thanks so much for the info Lisa
Cathy

It looks like you are in my zone. I planted pumpkins last year around the 20th of June (I remember because it was my sons birthday) and they were ready just in time for Halloween. I planted another batch on July 1st, and they set fruit and were turning orange in time for halloween too. So if you haven't started yet, you still have about a week. By the way, these were Jack O'Lanterns and Luminas, not giant pumpkins. I don't know if the giants would have enough time to mature before we get a frost!