Since you are using a source, make sure the subtitle filename includes "BluRay" or "BRRip." If you download a subtitle meant for a "Digital" or "WEB-DL" source, the timing might be slightly off due to different frame rates or studio logos at the beginning.
: While primarily associated with YTS rips, these subtitles are generally compatible with most 1080p BluRay versions of the film. subtitle Spider-Man.Homecoming.2017.1080p.BluRa...
It seems you are looking for subtitle files specifically for the Blu-ray release. Since you are using a source, make sure
: One of the largest databases available. It usually has dozens of versions for the BluRay release to ensure the timing (sync) is perfect. : One of the largest databases available
: Great for hearing-impaired (HI) versions and high-quality translations if you need languages other than English. Quick Tip for Syncing: