Yes I do, even when I know when I'll get home, plans can change.
A timer also can't tell me if my AC is actually on, may fail in the case of a power outage or I may forget to set it, as such using a timer doesn't provide a meaningful improvement over just turning on the AC when I get home and tolerating the heat for half and hour or so.
In the end, a timer has no feedback, so a closed loop system will always be better. I've been burned numerous times by open-loop systems in home automation, so I don't do that anymore. That's the second reason why I spend a lot more effort and money on sensors rather than actuators (the first reason being that graphs are fun).
You do realise that power draw likely averages less than 350 watts. Your A/C running for an additional hour or two a few days a month would cost you a dollar or two, max.
Given that the load is likely removing peak daytime heat, then sustaining a less-challenging night-time temperature, the net impact is probably even less.
The average central A/C will use 4000 to 5000 watts. I own the cheapest smallest window unit at the store and I just checked it's about 600W (4.8 amps @ 120V).
It's not horrible, but that's like half a space heater and most people spring for something bigger.
Peak draw. Duty cycle is about 1/3 that typically.
First hour use may approach peak, but again, most of that is incurred regardless.
5 kWh is $0.50 - $1.00, which is the cost of running an hour long for a day, the worst-case scenario. You'd spend a lot more on IoT kit (the Turris Omnia alone is $300) for minimising that cost.
