I would move to a larger pot right now. In the future I would plant your seed directly into the final pot size. Since auto's are on a fixed schedule any time lost to transplant shock can affect yield.
I have done some grows in 3 gal (11 liter) pots but I get larger yields with 5 gal (19 liter) pots. Key is to water thoroughly so every bit of soil in your pot is moistened so the roots grow to use every bit of soil.
Hey,
I think you can change the pot.
Since it's an auto, it will soon go into flowering.
With autos, you can put them directly into the final pot after the seedling stage.
I hope I helped you :)