It’s truly a personal choice.
When learning it is easier to go really short. It improves your control and allows you to get the feel.
I tried about 3-5 inches shorter than what I used for 1a and then made adjustments from there.
Just experiment with the length and enjoy the new challenge.
It really depends on the yoyo.
In all honesty, the best thing that you can do is just slowly that cutting your strings down and experiment with different lengths until you find one that you like.
I make my strings about the length of my arm.
Make your non throw hand string shorter.
Personal preference…one of my yoyos has a shorter (not quite sit down length but still considerably short) strings and I feel pretty comfortable with that. I’ve also tried a much longer string (custom made, longer than your typical brand new Duncan string…those are also fun to do loops with. With this said, made me think of this:
The key factor is the width of the gap. A wide gap will tend to loop up and a narrow gap will loop down. Conversely, a short string will loop up and a long string will loop down. The narrower you make your gap, the more you can balance it by shortening the string (and vice versa). If you’re experienced, you can make a wider range of options work, and it all comes down to what you like.
I have heard from quite a few 2A players that a good starting length is from the yoyo in your palm, to your shoulder. It seems that this is a good starting point for starting 2A length. Of course you can experiment with shorter or longer (Joseph Harris almost had 18 inch strings for a while, and Alex Garcia used almost full length I think) Just experiment and find what feels most comfortable.
The string should equal to the distance between the yoyo and your finger, when the yoyo is fully unwound. ;D
Seriously though it is an experiment thing. I use shinwoo loops on shortened string and YYJ Relics on full length.