Email sync timings

[jj14x]

Hello,
I searched these forums (I did!), but wasn't able to find this addressed already - so I guess I might be overlooking something very simple. Hopefully, someone here can point me to the answer

I have a TP2, with Sprint 6.5 Stock ROM. On the Email tab, I have the option of "automatically download ever 'x' hours". Let's say I select 'download every 4 hours' - how does the TP2 decide when to start the 4 hour interval?
In other words, if at 2pm today, I select 'download every 4 hours', will it download at 2pm, 6pm, 10pm, 2am and so on? It doesn't seem to be doing that - hence the question - it seems to not download any new EMail for a little over an hour - even though there are new Emails to download.

Thanks!