Break-in period 2015 Mazda 3

I may be getting a little ahead of myself since my car is still on its way from the factory, but I was reading that the 2014/2015 Mazda 3's have a 1000km (600 mile) break in period. I'll probably need to take the car on the highway the first weekend I have it (also. I want to take it on the highway!). If I make a point of not using cruise and varying my speed and RPMs as much as possible (in a range of 90-120km hr) this shouldn't affect breaking the car in should it? Am I being overzealous?

I was also reading it is recommended to do a oil change since new engines tend to end up with a lot of metal shavings in the oil during break in. What is the recommended time to do an initial oil change?

I think varying the speed and rpm will be fine while you ride on the highway. If your car comes equipped with a sport mode button I would not use it because if I remember right the manual at least in the US mentions not using it during break-in.

As for the oil change, I would follow the owners manual and wait for the first scheduled service. Engines are for the most part completely run in at the factory after assembly these days so most of the metal shavings should already be removed. A lot of the break-in is for all the other components on the car to make sure they are assembled correctly and are functioning right.

Breaking-in does not mean you need to drive as a granny does.
Avoid hard stopping and hard charging ahead. That is all. Yet, do not use Sports mode since your is a sGT like mine.
Varying diff speeds is good for the vehicle when it is warmed up.

I limited my top end to no more than 120 MPH (no cruise) and have not had any problems, yet.
Seriously, though, it used to be (just 10 years ago) that top speed needed to be limited to protect the transmission years. Today, that's less of a problem. I saw in the manual that there are 2 ways to know when to change oil.
1. Use the computer's algorithm to calculate when the oil change is due or
2. Notification is dependent by miles driven.
Or, you can set it to never remind you.

2014 Mazda3 Owners Manual
Pg 3-45 Driving Tips, Break-In Period

No special break-in is necessary, but a few precautions in the first 1,000km (600 miles) may add to the performance, economy, and life of the vehicle.

-Do not race the engine.
-Do not maintain one constant speed, either slow or fast, for a long period of time.
-Do not drive constantly at full-throttle or high engine rpm for extended periods of time.
-Avoid unnecessary hard stops.
-Avoid full-throttle starts.

and that's it! oops, I may have performed one or more "full-throttle starts"