For clarity when working specific techniques, pattern instructions may indicate the position of the carriage.

Commonly:
When the carriage is on the right, the row counter should indicate an even number.
When the carriage is on the left, the row counter should indicate an odd number.

Generally you start knitting with the carriage on the right and the row counter set to 000.

Is this a hard-and-fast rule? No... but this convention will help you keep track as you knit.