Precise Orbit File for Sentinel1 TOPS Data Auto Downloaded from SNAP

I used SNAP v7.0 and v8.0 to process the Sentinel1 TOPS datasets. I found that, the file name of the auto downloaded precise orbit file starts with the SAR data acquisition date
SAR data:

I am confused now. Should not I use the orbit file one day before the SAR data acquisition date?

I hope you can help me to figure out this problem.
Thank you very much.

Dingfeng Duan