timrick

The rolling period is only for the initial qualification of Gold and Plat status.

part of an email from Marriott on this topic

"Elite nights and status for Silver members are calculated by the number of
nights achieved from 1/1-12/31 of each calendar year.

As of August 17th, 2005 for our Gold and Platinum members, initial Elite level
achievement is handled differently. To achieve Gold or Platinum, a member only
need stay the required number of nights in any rolling calendar year. As an
example, let's say that you had 30 nights from September 1st, 2004 to December
31st, 2004 and 45 nights from January 1st, 2005 to September 1st, 2005. As this
would give you 75 nights in a rolling year, you would qualify for our Platinum
status.

As always, any Elite status you earn would be valid for the calendar year you
achieved the status in, as well as the next calendar year. In order to maintain
your Elite status for subsequent years, you would need to stay the required
number of nights during a fixed, non-rolling calendar year. Please note that
the Elite night counter will reset every January 1st of each new calendar year."

So, if this is your initial qualification for Gold/Plat. Then it's in fact beneficial to postpone the stays till Jan 06, you get the higher status for 2 years 06 + 07.