I suppose SW is as close as you're going to get for "as instantly as possible", although do be sure to read the stickied explanation on the myFICO Product Feedback board on how often and when you can expect SW alerts. If you go with SW, be sure to set your so-called "target" score to your most recent known score. Not one point above, not one point below, not where you hope you will be one day --the moment you get a notice for a new score, go in and reset your target to that number. And remember that SW is only tracking changes on your Equifax FICO score and report, not the other two.
I don't understand the TU Quarterly Monitoring system at all 
, and from what I've read, you don't get alerts of changing scores; only of possible identity theft issues.
And of course, we can't even buy our Experian FICO score, much less get a monitoring service to track changes. The products at the Experian site (and elsewhere) just track changes in FAKO scores, which is pretty worthless.
Are you coming down to a deadline where you need a specific score, such as for a mortgage app? Because if not, you can just subscribe to a credit report monitoring service and track the changes on your reports. When you see that new balances post, and that therefore your util has changed, you can then just decide to buy a score.
There's a great sticky on General Credit Topics that compares the different monitoring services.
If you go with a non-FICO product, just be sure to train yourself to ignore their scores and their advice, which are FAKO. Some FAKO advice, if followed, will actually hurt your FICO's.
I find it more convenient to get from this site. It's certainly not perfect here, but Equifax has had some amazing downtimes, and good luck trying to get through to their customer service.
It's the same product, so if the prices are about the same, I'd tilt toward the version from here.
Be sure to Google fico discount code coupon. You ought to be able to come up with something.