Today 29, Jul 2015 is the launch date of Microsoft Windows 10. Free Upgrade is already started for the users who has reserved it earlier.
You can check if there is a new hidden folder $Windows.~BT on you Hard Drive (C:\).
If yes, then voila its all setting up to you. The free upgrade is already started on your computer. You should be prepared, quite an amount of your Internet data will be consumed.
If no, have patience. Microsoft is rolling out this in phases, to prevent their distribution servers overloading. You will get it soon.