We did this back in November and it worked out really well for us
When we arrived at MCO we had to pick up some tickets from the Virgin Desk and our early entry invite was in the envelope
I have heard some people say that they have had to attend a welcome meeting in order to get hold of the invitation but we didn't need to do this
A Virgin Rep based in the US will call you a few weeks before your holiday starts and if they don't you can contact them via the VH website.
I spoke to a really helpful guy on the phone and he said he would leave the invites at the airport for us along with the tickets.
As we were staying at a Universal hotel we could access the park 1 hour before regular guests at 8am but the Virgin early entry got us in to WWOHP by about 7.30am
You have to use the early entry invitation within 2 days of your arrival
We arrived at the entrance at about 7.15am and there was a VH podium where a Virgin Rep was stationed to check your invite and park entry ticket
We were then asked to head to a turnstyle at the far end of the entrance gate where we were met by a Universal staff member
There was probably only about 5 of us in this group and we were walked right through to the WWOHP and The Three Broomsticks where you can help yourself to breakfast (basic muffins, OJ, toast, cereals and Porridge plus tea and coffee)
After a very quick bite to eat we headed out to take photos in a totally empty Hogsmead
If you want to do Olivanders I strongly advise that you do this first. The lines build up instantly. We got in line at about 7.55am and were the first ones in when they opened at 8am on the dot.
It takes hotel guests 5 or 10 mins to get to the WWOHP once they are allowed in at 8am so you really do get a head start on the crowds
Once you are out of Olivanders go straight to Forbidden Journey (check out the shops etc later as you can still get into the wand shop without seeing the show again)
If you love FJ (which you will) just walk round and do it again. We found it to be a walk-on until at least 8.30 ish and there is always the single rider line which is a great option but make sure you go through the standby line at least once as the inside of Hogwarts is excellent
We never found much of a line for Dragon Challenge but if you want to do Flight Of The Hippogriff do that fairly early as it's a slow loader
You'll them have lots of time to check out the shops etc
Make sure you have a Butterbeer (I prefer the frozen one

) and a cauldron cake if you haven't had enough sugar already
Have fun