I can confirm this same timing setup is the same on the Terastation TS-XEL and on the TS3400 series.
I wouldn't be bothered with sleep timers. As I mentioned in another post, these units were designed to be low power.
At 10 cents per kilowatt, it costs less than $5 monthly to run an LS220D 2 disk unit 24/7, and leaving it off for 12 hours- the savings on those is like a whole 2 bucks at best. Expect even less for an LS 210 single disk unit.
It is not worth it between the little savings, and the extra stop/start wear on the drive, which eats up power too and makes the power savings a wash more than likely. NAS are best left on with drives spinning.
Not to mention that to prevent file corruption, you need to disconnect any and all windows shares before you power it down. Windows holds onto files and often still thinks the files are still open on a NAS.
So if you really really really need to use a sleep timer, I would suggest using the idle drive spin down. It should have close to the same effect.
That or your only other option is to change the time/zone to where it meets your needs, which is going to totally throw off file dates.