How can I locate a specific time point in a very large file?

One function within LabChart that can be utilized to find a specific time point in a file is set selection. Click on Commands Menu and choose Set Selection...
Firstly check the box which states 'Active Point' to have a single point selection and choose whether the time point is based from the Start of Block, Start of File or Time of Day (this will likely reflect the time settings of your data file). Then enter the relevent time in the 'Time' box and the cursor will automatically move to the required location in the file.