If you have free evening calls and you travel across Canada, what counts as the "evening." Does it depend on what time it is where you are, or what time it would be in your area code? (And what time do free evenings start anyways??)
I'll start with the last part of your question first. Unlimited evenings starts at whatever time was specified by your plan when you purchased the plan. Some plans were for 7PM, some for 6PM and some for 5PM. Check your plan details in your self-serve account if you are uncertain.
As far as the first part of your question, first of all, if you are travelling across Canada, make sure you do in fact have a Canada-wide plan so that you don't incur long distance charges, and make sure roaming is off in case you hit a dead zone in the TELUS/Koodo network (unless you are okay with a potential bit of roaming). As far as whether it's local time or the time in your home base, I would assume it would always be local time of the zone you are physically in, not the zone you signed up in.
These posts, which asked a similar question, would seem to confirm this: