I started taking folic acid and a multi vit last month we ttc, i noticed that this month my period was longer than usual, is this a good sign or not?

Probable coincidence: Vitamins should have no effect on the length of your period. It is common for the length of periods to vary somewhat so this is almost certainly a coincidence. Folic acid/multivitamins lower the chances of birth defects so are important to continue. It takes an average of 6 months to conceive and is not worrisome unless it takes more than a year.