Yes, the German word for early is früh and so technically, früher should be the counterpart to earlier.
And it is in comparisons:
- Heute gehe ich früher ins Bett als gestern.
- Today, I’ll go to bed earlier than yesterday.
However, earlier is also used as a general indication of “when”, usually referring to earlier that day.
- Like I said earlier, this is not a good idea.
But here, the proper word is actually vorhin.
- Wie ich vorhin gesagt habe, …
And why not früher?
Well, because in such a sentence, früher actually means back in the day.
- Früher habe ich viel Sport gemacht.
- Back in the day, I used to do a lot of sports.
How far back does it have to be? Well, that’s not clear. But I’d say at least a couple of years. It definitely sounds like it refers to a past period that is over now.
It’s a common mistake and it can actually sound really confusing to a native speaker, so it’s worth fixing :).