Roughly how long until I need to transplant?

I would go ahead and transplant them. Though I tend to up pot early. Reason being Is being is so I don't limit the plants growth during it life cycle.

If they are autos you shouldn't be transplanting them. There is the potential for shock. You don't have time to wait with autos unless you go with a long strain like Dutch Passion's Auto Ultimate. Mine is currently on week 16 (supposed to be 12 weeks max) and was germinated in its fabric pot that was 16 litres (4 gallon) it has fallen over three times. Its huge. Maybe 5 ounces, who knows lol. Its on my profile if you want to check it out. Always germinate in the final pot dude.

Hi there You could do it now if you really wanted too… I like to wait until im watering them every 48hrs so i know the roots are well Advanced, Make sure there quite dry when you pot up makes it alot easier, Best of luck 🌱