Yep grab the sentence, not the two words separately. From the docs:
Do keep in mind that some keywords are harder to distinguish from others, and especially keywords with only one syllable (like ‘One’) might lead to false-positives (e.g. when you say ‘Gone’). This is the reason that Apple, Google and Amazon all use at least three-syllable keywords (‘Hey Siri’, ‘OK, Google’, ‘Alexa’). A good one would be “Hello world”.
Ok so i imagine that recording, i must do some spacing time (always different but near real world) between my “OK” and “GOOGLE” during my recording ? Well right ?
If i understand well , if i dont do that, my “clue sentence” will be too strict and will understand only one strict laps time during the 2 words.
Think of it not as two words, but rather as a single word with four syllables (“OKGOOGLE”) and yes, you need variation in spacing, pitch, speed etc. to make it robust.