Coachella is no different than any other music festival as to where the best time to arrive at a venue in order to get good seats and it is to get there as early as possible. It is said that the gates open at Coachella around 9am on Thursday. There will be huge amounts of traffic in and around the concert venue. While it is certainly a very good thing to be able to get seats close to the stage, a person will be sacrificing long waits in order to wait for the gates to open.
A lot of people tend to wait it out in the camping area where there is always something to do during the Coachella get together. If you are one of those who is looking to tough it out and arrive as early as possible in order to get the best possible seats, at least five hours before the gates open on Thursday is the best time to arrive in order to get the best seats.