Better be safe than sorry.
Apple might be fast and release a 6.1.1 update days after the new JB goes public and stop giving out 6.1 blobs in order to stop more devices getting jailbroken.
So update your devices to 6.1 as soon as you can and then use the latest redsnow version redsn0w 0.9.15b3 to save its blobs.
Redsn0w will save your 6.1 blobs and submit them to Cydias server. First connect your new device and turn it on, then use redsn0ws Extras->SHSH Blobs->New and point it at the 6.1 IPSW for your device.