Crowds will not be bad -- most schools are still in session that first week, and this year more then ever, schools will be extending their years due to the snowdays accumulated...crowds about 4 or 5 out of 10
I often go that first week. Weather can very -- it can be seasonable (high 80's low 90's) or it can soar into the high 90's...For me, as an annual passholder who goes multiple times a year, its the last week I would consider going until October when the weather breaks...you will also start to get those daily rain showers Florida gets all summer long