Please understand the following.
1. U have to send the demand notice within 30 days from the date of the cheque return memo.
2. Your notice should be through RPAD (register post with acknowlwdgement due)
3. As you send through RPAD, if in case the date of RPAD falls within the 30 days period then your well within limitation.
4. You have to keep the postal reciepts safely.
U need not represent the cheques
my suggestion would be to wait for the acknowledgement.
If in case the notice is not served and comes back then also u can file the complaint in the court in the following cases
1. not claimed
2. door locked
these endorsements are deemed to be served and you can proceed with filing the case.
I Hope this answers your question