Within how many days of a cheque bounce can I send a legal notice?

Once the bank has return the cheque, i.e. the cheque has bounced, you are required to send a demand notice within 30 days of such bouncing to the party who wrote the cheque (the drawer) informing him that you will initiate a legal proceedings against him under the Negotiable Instruments Act in case the amount is not paid within a stipulated time period (usually 15 days).

As per Section 138 of N.I. Act within 30 days after the cheque has been declared dishonoured due to insufficient balance you are required to send legal notice asking the drawer to clear off the debts and if it is not cleared within the next 15 days from the date of notice then you can file a suit according to the relevant section.
Thanks.

For dishonour of Cheque u/s 138 of N.I Act, the legal notice in the form of demand notice must be issued within 30 days from the date of dishonour of the cheque, giving the drawer of the cheque a further statutory time period of 15 days to pay back the claim amount. After completion of the 15 days statutory time period, if the claim amount is not paid by the drawer of the cheque, the cause of action arises.