Folinext is the brand name. It contains two ingredients: folic acid and methylcobalamin (vitamin B-12). It is an irrational combination not marketed in any advanced country. None of these agents have anything to do with menstrual cycle.
Folic acid alone (sold as Folet, Folvite, etc.) 5mg daily should be taken by any woman actively trying to become pregnant. It does not help in conception but will help to prevent birth defects in the baby. This should be taken throughout the duration of pregnancy.
Of course, one can have sex while on folic acid.