I've finally gotten my hands on a copy of this. It's a really good read. But I'm kind of curious what timeline this point of view is from. There are some sections that seem to imply that the "current year" is sometime in the 1470's or 80's. But then others it's very ambiguous.
If I recall...I believe it is intended to be ambiguous as to be usable by a broader spectrum of users...which is why many rumors have been circulated about the future of Realms products possibly being at least somewhat timeline ambiguous...
Where is this timeline located? My search just brings up El's FR.
There's no actual timeline in the book.
The OP was asking when in the larger timeline of the Realms is El's FR set.
From what I can tell, the book is set approx. 1479 DR and jumps back in time here and there to talk about parts of the Realms over the last century, in addition to talking about the design elements that went into the creation of the setting.
I think it's important not to look at El's FR as timeline specific, however, since a lot of what's in the book has to do with what the Realms is.
Look for me and my content at EN World (user name: sanishiver).