That sounds about right.
Most Chinese Americans (not the relatively recent Taiwanese or Mandarin-speaking immigrants, but the ones originally from the Cantonese speaking Southern provinces) came to West Coast & Hawaii starting at around the gold rush, until the US passed this:
That range is about 120-150 years, which is about 5-7 generations.
Most Japanese Americans in HI / CA are about 4th or 5th gen now (Also mostly from Southern prefectures...). They immigrated from the 1880's till this:
It's actually at a point where the newest generations of these groups shouldn't even think about that gen number anymore, as it seems a little ridiculous. This is probably due to lack of intermingling, as it's unlikely for someone to say 'Well, I'm 1/4 7th generation Irish, 1/8th 7th generation Scottish, 3/8 10th generation Dutch, 1/16 American Indian, 1/128th English from the Mayflower..."
As a side note, those exclusionary policies were all nullified by:
so that's why you see many Asians (including SE Asia and India) in 1st, 2nd and even 3rd generations now.