Understanding Society User Support

Hello,

I am reaching out to kindly request help on how to conduct longitudinal analysis using calendar year datasets.
1) Although online you state the published calendar year data are meant to be used for cross-sectional analysis, does that also stand for when we create our own calendar year datasets? Or is it meant to be a guidance only for when you release the pre-made calendar year data? If that is the case regardless, is there some way for us to still conduct longitudinal analysis after creating our own calendar year data?
2) Although you recommend using the w_month (sample month) to create calendar year data, would it still be ok to instead use the interview date instead, when the exact date is of great importance to the research question itself (i.e. when testing the introduction or removal of a social policy).

Many thanks in advance for your time and consideration.

Best wishes,
Marina