June 28th. It was a boilerplate e-mail from Disney Destinations, expressing excitement about my upcoming arrival and informing me about the effect of "ongoing enhancements." It specifically said that monorail service would remain suspended during my stay (although boat and bus service would be available and the walking path to the TTC would be open), but reported (in an attempt to give some good news) that the front desk in the GCH will be reopened by that time. It closed with an apology for any inconvenience, thanking me for my patience, etc., and gave the phone number I could call if I needed any "assistance" with my reservation. The end of the e-mail listed my specific reservation number and arrival date (8/21), so it appeared that the e-mail was definitely targeted to specific guests within a specific date range.
I actually replied to it with some follow-up questions including asking for confirmation on the absence of monorail service, and got the usual "thanks for your e-mail - we'll get back to you" response from Disney, but they never did.
As the prior poster noted, you can still walk easily to the TTC to catch the monorail there. However, in my particular case, I was just not interested in paying Poly rates (even with the discount I had) for a monorail resort that has no working monorail station, and is marred by multiple construction zones. The Polynesian is a big splurge for us, so if we're going to do it, I want it to be when it's fully open and operational. Not only that, but by putting off a Polynesian stay for a few years, we stand a better chance of Disney actually offering some kind of touring advantages to onsite and/or deluxe guests during our visit (something we'd hoped for when we booked at the Poly many months ago, but gradually realized was not going to happen). YMMV.