How much damage does over throttling slightly as you clutch up into your gear change do? I've been guilty of this a couple of times in my new ecoboost fiesta which ive had a couple of months now as the clutch is quite heavy and hard to get used to! Oddly I've driven two 2016 models of my car which is the 2015 spec and didn't have this issue with either of them despite the fact both models are exactly the same engine and gearbox configuration. It's particularly difficult to transition smoothly in to second from first. I'm massively paranoid about causing more wear than necessary especially as where I live our sort of driving on our horrible little roads causes enough wear and tear as it is
In the short term, there's no damage. If you keep doing this, you may see some extra wear on the clutch plates over time, shortening its life a bit. But I doubt it'll be noticeable.
The clutch and gearbox are built to deal with some slip when you change gears. The moment that causes the most wear for the clutch, is moving off from a standstill: the clutch has one plate standing still, while the other rotates at 1000-1500 rpm. It's built to withstand this for ~10 years. When you overthrottle a shift from first to 2nd, the speed difference between the clutch plates is usually less than this.
IOW, don't worry. And as you drive the car more, it'll become easier to get the gearchange just right.