Expect large crowds all weekend. It is the busy season, the hotels are all booked solid and Brazilian tour groups are all over the place. If your goal is to get on all of the IOA rides then being early is your best strategy since most early arrivers will be heading for WWOHP. If your goal is WWOHP keep in mind that there was a 45-minute wait for Ollivanders by 8am, one hour before official opening time. So even if you are early you will have a long wait due to the hotel guests. It has been relatively uncrowded between 8 and 10pm and it's been hot as all get out between 11am and 6pm. Rain may actually be a relief. Remember that you can get free ice water from any vendor who has a drink machine so bring a refillable water bottle and have a great time.
We are not big fans of express passes, we believe they are way overpriced and offer no help at all in WWOHP. Skip them unless you believe it is your only hope to get on the rides. You can buy them at any time so get there, walk around a while then decide. If you do buy them DO NOT USE THEM on a short line. Ask the attendant what the wait is and if it's less than 30 minutes save the pass until it gets more crowded. If I had a nickel for each time I've seen a family waste their passes on a walkon ride I'd have free express passes for life.
Thanks so much for the great tips! Our main goal is to do HP and we have 3 days to accomplish that. We will do other rides from 10-2. Wish we were onsite, but oh well, I guess it will be an adventure!??

I will wait on the express passes and see how things go... Loved the water bottle idea and the warning about the tour groups. Thanks again!