Android : Need to get the timestamp when a user has reached a specific location in android

I want to get the timestamp when a user has reached to a specific location in android. I've already got the longitude,latitude of the current location and destination. Now I need to check whether a user has come to that specific destination or not.(it should get the timestamp when a user has reached like 100m close to that location. Like in geofencing)

I am using an alarm manager which will be triggered every 5 minutes.

The geofencing is also do the same job. But I have already implemented this using alarm manager and this app has a tight deadline as well. So it is better to go with alarm manager to avoid major changes in the app.

Is it possible to do this with alaram manager and avoid geofencing? How to do this? Thanks.