ICE takes longer to turn on when starting car; good or bad?

This is the warm up phase of the car, I don't think there's anything wrong with your car. I would worry if the engine stays on and doesn't turn off or vise versa.

Does it turn on at all without going into gear?

 

The engine comes on straight away if you use the front demister or rear window heater. I notice sometimes the engine will fire up when you put the car in reverse too.

Maybe you used to reverse out before and now you drive forward instead?

Normally though, the car takes about 7-10 seconds before the engine fires up.

 

It should be in the 7 second range unless the battery is near empty or the HVAC is demanding a high load like immediate heat or super AC. Don't worry about it.

 

With the gen2 Prius the normal delay is 7 seconds. Putting the car in reverse will delay engine start up if the HV battery is reasonably charged.
This is because the engine actually fights against MG2 that runs in reverse to make the car go backwards reducing the available power in reverse if the engine runs.

John (Britprius)

 

ever tested the delay timeframe while going in reverse?

 

As long as the car is in reverse and the HV battery has enough charge the engine will not start. As stated above "somewhat clumsily" only MG2 gives you reverse. The engine tries to drive the car forwards because the Prius does not have a reverse gear. When the battery gets low the engine starts to use MG1 to provide current to help drive MG2.

John (Britprius)

 

The link below shows very effectively how reverse works. Scrolling down to the animation, if you slide the button for MG2 to reverse "downwards" the outer ring that drives the wheels goes backwards, and obviously forwards "upwards" for forwards. If while in reverse you you slide the engine slider to run the engine you will see it does not assist the ring in going backwards but tries to drive it forwards also driving MG1. In trying to drive MG1 it only puts more forward torque against the outer ring going in reverse.
Toyota Prius - Power Split Device

John (Britprius)

 

Is 65 mph the most efficient speed for the Prius? Where ICE runs at a minimum, only around 1000 rpm

 

This is not as simple as it seems. If you play with the animation you will see that at 65 mph MG2 is running at 3835 rpm. This remains constant for a given road speed. The engine can be running at anything between 1100 rpm and 4500 rpm while MG1 can be running at anything between -6300 to +6200 with the car still doing 65 mph. This particular animation is not for the gen2 it's actually for gen1 the system is exactly the same, but rpm's will vary because of different gear ratios.
The most efficient speed is somewhat lower than your figure.

John (Britprius)

 

I pay no mind to when the ICE turns on or off. I'll start being concerned if my mileage goes down.

 

Curious... Instead of waiting, I usually tap the gas pedal to activate the ICE during cold starts. Is this bad practice?

 

If your first action is reversing it would be better not to tap the pedal, but it will do no harm to the car.

John (Britprius)

 

It's a habit that I like to get the oil pumping for the first minute before putting the car into gear.

 

When reversing the engine normally would not be running, and fights against the electric motor that powers the car backwards.

John (Britprius)

 

It may not seem like fun, but I've gotten incredible reliability out of the vehicles I treated gently.

 

Unless you prevent it from turning on (like choosing reverse) the gas engine will start 7 seconds after startup. If it doesn't there is something strange going on. People are notorious for not knowing how to count time, so I would ask you use a stopwatch (like on your cell phone or an actual stopwatch) to get the time between when the car says "READY" on the dash to when the ICE starts. Do nothing but turn the car in READY, no shifter movements. It should be 7 seconds with anything above a low SOC battery.

Motor Generator 1 and Motor Generator 2.

They are the 2 electric drive motors that couple with the single petrol powered engine to form the hybrid drivetrain. They also act as generators producing power at various times for various reasons. Hence "MG".

 

I have trouble picturing what you claim.
How is the engine fighting against the electric motor?

I'm supportive of forcing the early start--it gets me thru phase 1 sooner before I need to propel the vehicle (forward).

 

Nothing is "fighting." The power sources are coupled to the drive-train through a power-sharing differential.