Hi Suvankar,
Normally there should not be delay in replicating Products/Accounts/Contacts. Try replicating one of the object like Customers and immediately check in WE02/WE05 to see if the IDOC is getting delivered to HCI immediately then check in HCI (eclipse) to see if the message came in and is with the status "Completed". Once you see the status as Completed in HCI the message was successfully delivered to C4C which you can check in C4C web service monitoring. I think this will help you in narrow down where the delay in processing the message.
Also check if the IDOC is set to Collect idocs which might be the reason for the delay.
Thanks,
Prakash