It's not been confirmed yet, but it's likely that all, or if not, the majority of the title will be available during this early EA Access period. Similar to different EA Access promotions in the past, this early play time will be restricted to just 10 hours of gameplay. Players can close down their game and open it at any point to ensure they get the most out of those 10 hours.
Once the 10 hours are up, players will be locked out of playing, but they will be able to continue their progress on the full game a week later.
To make the deal sweeter, this promotion will apply to those that have not yet pre-ordered the game. This means that players with EA Access will be able to get a taste of the Mass Effect Andromeda experience before purchasing it. Once again, players who go through this route will be able to continue their progress after launch day if they choose to purchase the game.
Unfortunately, the EA Access program is not currently available for the PS4 version of Mass Effect Andromeda - PlayStation owners will need to wait the extra week to play the full version, and it's unlikely that a trial version will be available.