Since you have a BluRay rip, the subtitles should sync perfectly. However, if the text is appearing too early or too late, you can fix this instantly in using these shortcut keys: Press H : To delay the subtitles (if they appear too early).

If you don't already have the .srt file, the most reliable sites for this specific BluRay release are:

Search for "Bridget Jones's Baby" and look for the version labeled "BluRay," "x264," or "720p." OpenSubtitles: Great for multi-language support.