Hi there
Thats always a difficult one!! I would say it depends on the cry -if it's intermittent and not full blown - worth waiting to see if they settle - if its full on screaming - don't wait that long. Other options - can you get in the room without being seen? thats what I always used to try and do with my DD so I could see if she was trying to settle herself or actually needed my help!
Murphys law states you always pick the wrong option!! Stick with it!!
HTH
Clare
Mum to spirited angel Anna and my little insomniac Nathan 24 weeks