diff --git a/doc/0.getting_started.md b/doc/0.getting_started.md
index 81b9704..8f3a92b 100644
--- a/doc/0.getting_started.md
+++ b/doc/0.getting_started.md
@@ -186,7 +186,9 @@ under the `constraints` key. The available constraints are:
   form. `mode` should be either `PUBLIC_TRANSPORT`, `WALK`, `BIKE` or `CAR`.
   Beware that `time` constraints are in **seconds**. You should take
   some margin as the travel time computation is done with found nearby public
-  transport stations, which is only a rough estimate of the flat position.
+  transport stations, which is only a rough estimate of the flat position. For
+  `PUBLIC_TRANSPORT` the travel time is computed assuming a route the next
+  Monday at 8am.
  * `minimum_nb_photos` lets you filter out posts with less than this number of
    photos.
  * `description_should_contain` lets you specify a list of terms that should