About Celtel Gprs On Pc

Hi,

i got to connect my phone to my lappie via bluetooth and browse using the Celtel network. I got a cue from a fella here i had to recharge my phone to be able to browse. But the rate at which money was deducted was quite fast. If i browse late at night, say midnight, would there reduction in the data charges? Or is there a way it can be done free? Would 'ppreciate your help, thanks.