What happens next?

How to date old photographs
Look at dress and hairstyles in the images.
If your image has people in it, their hairstyles and clothing styles can be an indicator of the time period. Take a look at clothing catalogs and photographs with known dates.
These can help you narrow down a timeframe for your image. Remember that things like style can be regional, so look for images of people from similar regions or spheres of cultural influence.