How long is it supposed to it take a person to die from lung cancer?

Depends on stage: Stage 1a - maybe never (die of something else) stage 4 - several weeks to few months.

Variable: There are different cell types and growth rates( called doubling times)! the small cell, undifferentiated as an example is very fast and most folks die within a year(?Or 2). Some of the squamous cancers are slower and may be quite large and asymptomatic even when large. Very variable depending on type, size, location, stage and response to treatments.