Just some notes here:
1. In IQAS, course by course ECA is called Specialized assessment
2. It will take 13 weeks after sending the AOR. They usually take 3-4 weeks to send AOR. So, it could be 16-17 weeks in total. To reduce cost and time, you can fax them using hellofax.com at no cost.
3. Send your documents to CIPS at the middle of ECA processing, so that they can start reviewing. Also mention that, IQAS will send the report within 1-2 months. I am saying because the current processing time of CIPS is ~6 months.
4. Work Reference letter is same as what you would prepare for EE. Just make sure the points of the letter touch most of the required topics (BOK) for CIPS.
Best wishes and wish me luck too