Earliest complaint of OSMF patient is:
Prodromal Symptoms (Early OSF) 
This includes a burning sensation in the mouth when consuming spicy food, appearance of vesicles especially on the palate, ulcerations or recurrent generalized inflammation of the oral mucosa, excessive salivation, defective gustatory sensation and dryness of the mouth. There are periods of exacerbation manifested by the appearance of small vesicles in the cheek and palate. The intervals between such exacerbations vary from 3 months to 1 year. Focal vascular dilatations manifest clinically as petechiae in the early stages of the disease.
Reference: Shafer’s Textbook of ORAL PATHOLOGY Eighth Edition page no 148
Blanching
Burning sensation
Restricted mouth opening
Shrunken uvula