iPhone How would I stay on 7.0.6, unlock phone and keep jailbreak?

[famoussasjohn]

Since iOS 7.1 is coming out soon, I was wondering how I would keep the phone on 7.0.6? I bought an iPhone 5s about a week ago from T-Mobile (got the iPhone 5s for $200 cheaper from them since I traded in a Blackberry.) and they have the 40 day requirement before you can request an unlock from them. Is it a necessary step to restore the phone, or can I just pop in my AT&T Sim card and input the carrier settings and be good to go? I don't want to restore and be forced to use 7.1 and lose my jailbreak.

I was reading this - http://support.apple.com/kb/ht5014 and it says

If you have a SIM card from a carrier that is different from your current carrier, and you've received confirmation from your current carrier that your iPhone is unlocked, follow these steps:

1.Eject your SIM card and insert the new SIM card.
2.Complete the setup process.

but I did a recent unlock request with AT&T for my iPhone 5 that I'll be selling and it tells you that you have to do the restore for it to be finalized and such.