I had that same question of one of my mentors. I have spent most of my life in the outside the internet world of business, and the tenor and pace of work tended to slow somewhat during the summer months as people get distracted by vacations and such.
I was advised that it is not quite the same in the IM world as people are doing business essentially 24/7. While that may be true, simple common sense still applies. Find out, if you can, who else might be launching around the same time and if you are competing for the same pool of customers or affiliates.
If you launch against a "guru" launch, you can still do okay, but you need to take care to not get lost in the clutter.
It appears that the last couple of weeks in June are going to be pretty interesting in terms of new products and services being made available.
Jim