Understanding notifications - Lock Screen

Hi,

I own an Ipad which is running the current IOS. I often get work from one client who emails a lot of people asking "are you available ASAP?" It is basically whoever responds first gets the job. Usually fairly early in the morning.

I've figured out how to get notifications when I am using my Ipad, however it doesn't make a sound if it is in the locked screen. I use Gmail, and ideally I want notifications from this one client. I do not want my Ipad giving me a sound alert every-time I get an email in the middle of the night.

How do I set this up? I am ok with it sending me notifications from all Gmail as long as it is not when I'm sleeping.

Thanks for any help!