(Britain) Fairly recently.

Example: Used other than as an idiom: see not,‎ long.
  "How long have you been in the service?" ―"Not long."
1976, L. P. Davies, Possession, The Crime Club, ISBN 0385110758, page 138:
  " […] You ought to try one of these biscuits. They're good."
  "I've not long had breakfast," Morgan told him.