When my little guy had a GA they used the gas to put him under and they didn't do anything until he was under.
They go to sleep very fast once they start breathing the gas. Be warned that he will suddenly feel very heavy and floppy in your arms - it is a bit of a shock to feel your child so limp and I started crying. I think that most Mums cry.
They let me into recovery so when he came round I was right beside him.