1. You can read this here:
http://track-chinapost.com/China_Post_Arrival_Time_Stat.php

Hope this help.

1. First thing first. Here is the tracking of your parcel:
China Post Register Air Mail Tracking System
Parcel No.RS263472302CN tracking result
2016-10-10 21:40:39.0 Dongguan city Post Office eCommerce dept. parcel center received
2016-10-10 22:21:39.0 Dongguan city Post Office eCommerce dept. parcel center customs scan
2016-10-10 22:27:16.0 leaving Dongguan city Post Office eCommerce dept. parcel center ，next station Dongguan center
2016-10-11 12:54:41.0 Guangzhou Transit Station export security scan
2016-10-11 13:22:54.0 Guangzhou Transit Station export customs scan (domestic transit )
2016-10-13 01:54:27.0 Beijing Transit Station export security scan
2016-10-13 14:34:32.0 Beijing Transit Station export customs cleared
2016-10-13 22:10:00.0 arrive Beijing Airport
2016-10-13 22:15:29.0 leaving Beijing Airport going to next airport/seaport
2016-10-24 11:14:00.0 Beijing departure

2. You can notice just like me that your parcel did not depart China before the 24 Oct because there was no room for the mail bag.

3. You need to understand this is normal condition. Your parcel has been on the road for 18 days but for 11 days it was at the same place so technically your parcel has been on the road for only 7 days traveling time.

4. And also never forget the 8 to 13 days estimate arrival is that, only and estimate arrival. It's not solid rock, it's only giving you when you can expect your parcel.

Hope this help.

1. You should receive your parcel before the 11 Nov, if not then contact seller to tell him your have not receive your parcel and make some arrangement with him.

Hope this help.