• 03.010 and it seemed supper-time would soon do the same.
• 07.066 or it will be supper-time before it is ended.’

Supper-time, in a land with tea in the afternoon or early evening, is quite late indeed, well after dark in any case.

The dogs say it is a fantastical time about which many stories have been told and many ballads sung, but which does not come in truth.

The OED says, in contrast, that it can be hyphenated in the examples.

“supper time, n.” OED Online, Oxford University Press, June 2017, http://www.oed.com/view/Entry/194604. Accessed 21 September 2017.