Just called Verizon yesterday on an unrelated matter and found out that the Marshmallow Update is now on hold.
I actually spoke with someone helpful at Verizon on Friday... A Customer Service Rep named Kenny said that us Galaxy S6 users should see our update on our around April 13th.
I spoke with Verizon and they said to contact Samsung regarding a timeline for the update to the Galaxy S6. Samsung said that it was up to Verizon... round and around we go!