It's no secret that in a matter of hours Microsoft will start distributing Windows 10 upgrades with the goal of getting to dump older versions in favor the latest edition.
While it will send out the upgrade automatically, corporate IT managers have control over which of your computers will get the new version of Windows when your organization is ready for it. Microsoft is also parceling out the upgrades so that not everyone is getting upgraded at once.
Furthermore, if you're using a Windows Enterprise version, systems administrators will control the upgrade. Individual enterprise users won't be able to get the automatic upgrades being sent out by Microsoft.
For businesses that aren't running the Enterprise version of Windows, Microsoft will deliver the upgrade for computers running legitimate copies of Windows 7 and Windows 8.1. You should have already seen a Windows logo appear in the desktop taskbar, down in the lower right corner of the screen on each computer. If you click on that logo, you'll be given the opportunity to reserve a free upgrade.
When that upgrade is actually made available by Microsoft depends on two major factors. First, it depends on whether Windows 10 is ready for that specific computer. Not every hardware driver is ready for distribution, and Microsoft will have collected information on your hardware when you reserved the upgrade. You won't be given the opportunity to upgrade until the package is completely ready.
In addition, Microsoft is using a first-come, first-served approach so that, all other things being equal, those who reserved their upgrades first will get them first. But that doesn't mean you have to reserve your upgrade right away, or if you've reserved it, that you have to pull the trigger on the upgrade right away. In fact, in most companies, you should wait to upgrade most of your computers.
The reason is that virtually every new operating system, not just those from Microsoft, has teething problems. You can assume that there will be glitches that will take a while to fix. You can also assume that at least some of your critical applications will have compatibility issues, especially if they're custom applications.
With that in mind, here are the steps you should take.
You need to identify a few Windows clients that need to be upgraded immediately so you can test the upgrade. This testing will have two goals. First, you need to make sure it works on your company's standard hardware and software. Second, you need to determine how much of a learning curve to expect for your company.
If you haven't already installed the preview version of Windows 10 on your test machines, then reserve your copy now and try to get at least a few copies for testing as soon as you can. If necessary, you can purchase Windows 10 at retail and install it immediately as soon as it arrives in stores.