When is service tax to be paid

Dear All,

My quest regards to the payment of Service tax reg. GTA.

I understand that the dues are to be paid on / before the 5th of every subsequent month.

Let me say I transport a material (for which I require to pay ST) on the 10th of a month A.

The Bill is raised on the 7th the next month B.

Since I get 30 days credit for payment subsequent month C,

Which date / month should be considered for paying service tax dues.

In which month can I take credit of the paid service tax due.

Shall greatly appreciate your clarification.