Download the update at night
Firstly, start the 5GB+ download at night. It is going to take a while unless you have a really fast line. You may as well let it do its thing while you are sleeping. My download took about three and a half hours with a roughly 4.5 Mbps download rate.
Just be patient and wait
Secondly, the installation process may seem like it is going to be pretty quick but don’t believe the time estimates at all. My MacBook Air started off at a sprint and then seemed to stall at “1 minute remaining” for about an hour to an hour and a half. I Googled this and the advice people gave on various fora is to “just wait”. It eventually finishes and boots up into your new look OS.
All those updates and performance tweaks
A number of updates only become available once you have installed the new OS. I have iWork and iLife apps installed on my Mac and those need to be updated too. Some of those updates are hundreds of MB and that takes time too.
Your Mac will also do some sort of performance tweaking in the background so the cumulative effect of the app updates and the performance tweaks may mean that your Mac just won’t be too interested in doing what you want it to do for a few more hours. Best thing to do may be to assume you won’t be using your Mac just yet and either do what you need to do on your other devices or go do something else.
Good times to update
A good time to update is when you won’t need to use your Mac for about half a day or so. You may want to wait till the weekend to update (that starts tonight). Start the download when you head off to bed (and after your precautionary backup), start the installation just before breakfast and then start the updates before you head out with your family or friends for your late morning recreation.
You may still need to update a couple apps here and there but that should take you to a point where most of the bigger updates are done and, hopefully, your Mac will have completed its performance tweaks so your Mac is usable again.
@pauljacobson heh heh. I no longer install new OS's on primary devices. Too much risk.
— Nate Kettles (@NateKettles) October 17, 2014
Another piece of advice to bear in mind is to consider waiting for bug fixes before updating. I never do that and always update as soon as the update is available but the experience does tend to improve with those smaller releases.
So far I like the update. I like the design and what I’ve played around with so far. I’m just waiting for everything to finish updating so I can get back to work …