Regarding the S2 Visa

Hello,

Me and my wife we have each one a 1 year study X and we have to start at the end of September. We would like to take with us our daughters, 1 and 4 years old. Do you think that we can apply for the S2 for them before going to China, or we have to first go there and apply later?
For us it will be extremely important to go there together all of us and I wonder if this is possible.
Thank you in advance for your advice.
A. Costel