There is a lot of reading out there on the various types of instabilities, but generally the timescale for these effects are in the microsecond to millisecond range. I think particles move toroidally in the transsonic range, which depends on the temperature (which is a gradient from the core). This would be in the range of 300-1000 m/s in a device with a circumference of a meter or less (for most science machines made so far). I think it only takes a handful or orbits for an instability to grow. It depends on how much abnormal magnetic shear there is. I’m not comfortable saying more.
I can’t edit this post for some reason so I’ll just put my correction here.
I attended a presentation today that, at one point, showed toroidal flow rate over radius in a 1m major radius device. It ranged from 30 to 100 km/s. There are many effects operating at different timescales. Turbulence is among the shorter timescales, making it difficult to simulate and why it is only now the current focus of many researchers.
https://www.energy.gov/science/fes/articles/zero-tolerance-t...
http://www.ccfe.ac.uk/assets/Documents/POPVOL17p082509.pdf