You're doing it backwards. Buy the cheap photos and learn on those - then you don't have to worry about when to flip. Flip them when the plant is big and healthy - however long it takes to get there from overcoming growing errors. Once you've gotten good at growing, then run an auto when you know you won't stunt it from common new grower errors.That is kinda the goal, Use the 2 buck autos to learn, then a few months down the line get some better seeds once I feel comfortable with the process.
You should go into your first grow with the expectation of learning, so talking about yielding 5oz is lmao. Unless you have gardening experience with other crops, yield should be the last thing on your mind. Then if you make it close to the finish line and your buds get molded up, you won't be heartbroken.