ST applicability for Coaching institute

One of my client is providing training to the students,

they are collecting enterence deposit from student which can be refunded within 5 days if student wish to discontinue.

- they can issue "deposit receipts" and account that as "deposit a/c" wihtout service tax, if refunded WITHIN 14 DAYS, no service tax.

Upon confirmation, the remaining fees are collected either upfront or on installment basis.

 - when confirmed they have to transfer the deposit to "fees installment a/c" and charge service tax on gross including deposit.

Now my question is, after introduction of POINT OF TAXATION , at wat time and upto what amount the income should be recognized and ST should be paid on what amount? Full fees receivable or installment received.

- every installment will have a receipt naturally, so the service tax also would be paid as per receipt, 

And can we show the initial enterence fee as deposit and upon confirmation the same is transfered to fees account.

- already replied in 1st para.