With that aside, there are several methods floating around that allow you to bypass the waiting period in Windows 7 or Windows 8.1, meaning you can begin the upgrade to Microsoft's shiny new consumer OS now. The method shown here only requires that you add or edit a registry value. It worked for us on multiple systems, but we can't guarantee it on every system.
STEP 1 - Open RegEdit and Navigate to OSUpgrade Key
In Windows 7, simply click Start (Orb) and type regedit into the search box. Open it when it appears in results. You may encounter User Account Control prompts.
In Windows 8 / 8.1, either right click or tap and hold the start button and then choose Run. Type and run regedit. You may encounter User Account Control prompts.
With the Registry Editor now opened, you need to navigate to the OSUpgrade key, which is located at:
HKEY_LOCAL_MACHINE / SOFTWARE / Microsoft / Windows / CurrentVersion / WindowsUpdate / OSUpgrade
NOTE: If the OSUpgrade Key is not present under WindowsUpdate, then right-click on WindowsUpdate and create a new Key called OSUpgrade, then click on it. It would be unusual if it doesn't exist. Please make sure that you have been offered and have reserved a free upgrade to Windows 10 on the machine you are using!
STEP 2 - Create new DWORD (32-bit) Value
As shown in the image above, right click in the right-pane in Regedit (remember, you should have the OSUpgrade key opened as shown too). Under New, click DWORD (32-bit) Value.
A new DWORD value will now appear in the right-pane and you will be able to edit the Name. Type "AllowOSUpgrade" (without quotes) and press Enter.
STEP 3 - Edit AllowOSUpgrade DWORD Value
Now simply double-click on AllowOSUpgrade and you will be able to edit its value. Make sure Base is set to Hexadecimal and under value data, type "1" (without quotes) and then click OK. Tap F5 to refresh the regedit window if needed.
If all went well you should be able to see AllowOSUpgrade in the right-pane with the OSUpgrade key open, and the value should be 0x00000001. If so, close Regedit.
STEP 4 - Open Windows Update in Control Panel
In Windows 7, click Start (Orb) and type Control Panel. When it comes up, click it. Now click Windows Update (you may need to change "View By" to large or small icons to find Windows Update). You may already see the "Upgrade to Windows 10" option and be able to click the Get Started button. If not, click Check for Updates and wait a while.
In Windows 8.1, we are looking for the Destkop Control Panel and NOT PC Settings. Open Control Panel by swiping in from the right edge of the screen, tapping Search (or if you're using a mouse, pointing to the upper-right corner of the screen, moving the mouse pointer down, and then clicking Search), entering Control Panel in the search box, and then tapping or clicking Control Panel.
Now click Windows Update (you may need to change "View By" to large or small icons to find Windows Update). You may already see the "Upgrade to Windows 10" option and be able to click the Get Started button. If not, click Check for Updates and wait a while.
Conclusion
In the cases we have tried, this worked to get around the delay to start the upgrade to Windows 10, and we hope it works for you too. There are other manual methods too that we can link to if necessary (let us know in the comments). Additionally, we found these instructions floating around and don't know where / who the source was, so if it was you (or you know the source), let us know so we can credit you by name / twitter / blog / facebook etc.