This recording of Thomas Edison from 1906 is full of "uh" as conversational filler or "verbal disfluency". It doesn't sound much different than speech today. I'll see if I can find an earlier recorded example http://www.nps.gov/edis/photosmultimedia/upload/EDIS-SRP-0158-06.mp3

All of this has only discussed English conversion fillers, which is what I assume is what you're mainly interested but maybe you'd like to know about other languages as well. In Turkish, among the most common are şey ("thing") and yani ("that is"). One can tell that they predate the massive language reform of the 1930's, which attempted to get rid of all words with foreign etymologies--şey and yani were both originally Arabic words. In fact, yani is still used as a space filler in Arabic, at least as far as I can tell from eavesdropped conversations at airports, and if it was borrowed into Ottoman Turkish a space filler, I can imagine it has been used as one for quite a long time (actually, I looked it up. The Turkish etymologist Sevan Nişanyan notes that it was already in use ~1300 with the meaning "that is to say", so it is a pre-Ottoman borrowing into Turkic languages, though maybe not in the specific space filler sense).

Geoffery Lewis, in his book the Turkish Language Reform, recounts that şey's banning was unlikely because şey is:

a word without which many Turks would find difficulty in conversing, for it is what comes automatically to their lips when groping for a word or a name, or thinking what to say next. It is used much like the English 'what-d'you-call-it' or the French chose and, as a sentence opening, like 'Well now' or 'I'll you what', or 'Il-y-a une autre chose qui est celle-ci'. Atatürk wanted it abandoned as it was a borrowing from Arabic (Had that happened, an English analogy would be the inhibiting effect of a ban on 'y'know' or 'basically).

Eventually, as Lewis recounts, one of the reformers was able to win Atatürk over with the argument:

'Don't do it, Pasha!' I was saying, 'If a miracle were to occur and all the dead Turks in Anatolia could suddenly be resurrected, the first word to come out of their mouths in unison would be şey. That's how Turkish şey is.'

Which, I think indicates just how ingrained it was in Late Ottoman daily speech.

I'm not seeing any responses to the words such as like, you know? So all I know is 1800's English literature, where the 'extra' words and phrases are such as "wouldn't you agree" used rhetorically as our "isn't it" or "y'know". Also "verily", "are we not". That's all that spring to mind right now. They also did use ums and ahs then but fiction rarely wrote conversational place holders, preferring very correct grammar. Reading transcripts or affadavits from the time would help answer this because they are word for word. Also I think Hansard was established by the late 1800's. That's a written record of what is spoken in Parliamentary discussions. Hope I've helped a bit.

Is conversation fillers the right term?