Were you told - "descend and maintain...." or were you told "cross XYZ at 6,000'...." ?
In the first case you have to descend at least 1000' FPM. So his technique would be wrong. If the FMC TOD is a mile away delaying the start of descent is not a crime.
In the second case his technique is an efficient way to run the a/c(not for a 2000' descent but as a general technique). Nothing dumber than seeing guys descend well before TOD, especialy with a tailwind.
If the VNAV generated path is barely ahead delaying the start of descent for seconds, or starting a gradual descent until the VNAV descend profile is captured, are also acceptable techniques.