When do I transfer from dixie cups to larger pots?

The title speaks for itself. I've had my plants in dixie cups for a week tomorrow. They are all about 3-4" high. I know it's not quite time yet, but when do I know when it is time? Thanks.

When seedlings start growing their three-bladed leaves, they get moved from plastic cups of inert seed starter soil into larger containers full of a nutritious vegging soil mix. It sounds like it's time.

yeah it couldn't hurt to put them in early. Only problem you would have is if you wait too long and they get root bound and stressed.

when the roots form a nice spiral at the bottom of your cup, you know youre good to go.