Vibrato and intonation question
Is it better to find the correct note before vibrating or do you correct the note while vibrating?
Find the correct note before vibrating. Vibrato should only be used to add colors and expressions, not to correct wrong intonation
Finding the correct note while vibrating is what professional violinists affectionately call "faking it".
There is a legend that when complemented on his perfect intonation Jascha Heifetz said his intonation was no better than other virtuosos, he just corrected faster. Vibrato motion plays a part in that.
The best violinists know where the note is before finding it. Otherwise you tend to get a delay with the vibrato that makes the overarching phrase sound disjointed.
An incorrect hand posture or vibrato mechanics can distort otherwise good intonation. Some recommend doing the scales both with and without vibrato. I should try that. Vibrato shouldn't be used to correct intonation, but it can cover over those fine distinctions between Pythagorian and Just intonation. The audience will hear what they want to hear.
Depends how wrong the note is? I play many notes where a slight rotation on the fingertip corrects it. That kind of correction can be combined with vibrato. I wouldn't try it with a quarter-tone, though.