How to get child credit, since my kid does not have SSN?

How can I claim the Child Tax Credit if my child does not have an SSN? I am an immigrant on a J1 visa. What is the process for obtaining an ITIN for my child? Do I need my child's ITIN before filing my tax return, or can I apply along with the tax return? Additionally, does TurboTax assist with obtaining an ITIN?