a reservation will guarantee you entrance into the land up to an hour before your reservation time. As of now the park is opening at 9am that day right, so it won't give you access earlier than 9, so I would say, no in this case
if you go on
MDE click on the SWGE status and access. On the top where it says Curremt Status it will say join boarding group, then it will give you a number of BG. Then underneath you will see the Now boarding.
You will receive a push notification when your BG is ready to go in
If you don't have access to MDE on your phone then BG can be done in guest service kiosk around the park