As you have asked about the HSSC Canal Patwari interview schedule, I think it has not been declared yet.
You can find about the schedule from HSSC website.
I found following results from its website

corrigendum regarding clerks
corrigendum against Advt. No. 7/2015
Revised examination notice - 1/2015 and 2/2015
Corrigendum 5/2015
Corrigendum Advertisement No. 4/2015 regarding extension of date for sending application for the post of PGT Political Science.
Corrigendum regarding change in timing of written test for the post of Dietitian of Health Department.
Interview Schedule for the Post of Account Assistant Advt No. 3/2008 Category No. 61 under court Case
Interview Schedule for the post of Pharmacist and Dispenser, Ayurveda against Advt. No. 2/2013, Cat. Nos. 19 and 06.
NOTICE TO THE PHC (BLIND/LOW VISION) CANDIDATES ONLY (INTERVIEW SCHEDULE)
INTERVIEW SCHEDULE

You can also check about it, by following the steps given below

Go to HSSC website

Then click on Interviews, the page open look like


Here you will find the information regarding the interviews.