Finally: the Win10 upgrade is going to *start* on 29 July, but I strongly suspect it will actually take several weeks to propagate to all requestors...and IIRC, they said it was more or less first come, first served. The line ahead of you is already rather long.
Remember, we're talking 3 Gb downloads to each box, and there are hundreds of millions of potential upgrades. There are similar situations...Ubuntu version upgrades in April and October, Mac OS X upgrades, Android upgrades...but this will dwarf ALL of them. I am actually concerned that this might be like the situation in London, during the Olympics, when the city's wireless infrastructure was *swamped* due to the massive use.