Can network access be controlled?

I just got to sync iPhone's calendar and contacts with google's... it's awesome!! Problem is that everytime I access either calendar or contacts now, it checks for status. As I don't have a contract with data flatrate, I would like to decide when the syncing has to take place.

Syncing twice or tree times a day when I have wifi around is more than enough.

I've already switched "Fetch New Data" from "off" to manually and "Mail, Contacts, Calendars" under "Advance" are set to Manually as well.

Could somebody help me with this one??

Thanks in advance,