NZFF

Regarding flight plans & approaches.
Scenario.
I depart NZDN for NZCH.
Direct flight on AP at 5000ft.
Approach will be for ILS 02.
At what point is it normal to activate the approach.
It would appear I can do it anywhere along the route.

Which aircraft and what type of nav system are you using? Is there a STAR and approach loaded?
You have not provided enough detail to answer your question.

Sorry, I tryed to keep my question simple.

Ive been using the SR22 & SF50 on the same route, to get familiar with the G1000.
Regarding nav system. Whatever is the default.
No STAR, approach is ILS02

I load the plan before departure & the approach on route.
Whenever I activate the approach, the aircraft deviates from the plan to line up for the approach.

Hence, my original question.
And I'm using XP12

As far as I know this is the correct response when the approach mode is activated.
The Approach mode should be activated when on an intercept to the final approach course . There really isn't any point in activating it any sooner.
You didn't mention which sim you are using but this might be a moot point anyway as most are similar in nav behavior.
Hopefully someone more familiar with the G1000 will chip in.

It has been a long time since I did my Garmin rating but just got off the phone to a current G1000 driver.

As noted, you have 2 options "load" or "activate" an approach. Loading an approach will put it at the end of the flight plan and the approach will automatically activate approaching an initial fix or in the case of an ILS within 1 dot of the localiser.

If you activate an approach, it take you directly to the initial fix ignoring the current flight plan , STAR etc.

Hope that helps.

That's interesting, I haven't actually tried flying the plan with the approach only loaded.
I assumed that would have just taken me directly to the airport.
I'll give it a try later today.

Well it didn't work for me.
I tried a flight from NZDN to NZCH.
Using the Cirrus SF50.
Used SimBrief to create a simple plan.
Loaded that into the G1000.
Added the ILS02 approach.
Flew the plan & it just flew right on past.
Tried another from NZCH to NZWN.
Same setup.
Flew right on past.

If you can put a pic of the plan up at the start of the ILS and also the FMA modes that will help see what's happening.

I took a screen shot of the flight plan but couldn't work out how to attach it here.
However, I have watched some more YouTube videos on the subject & will put that knowledge into practice.
As I see it, unless you edit the plan & link the main route to the start of the approach, then you have to manually make the change at some point.
Hence my original question.