it a watse of time getting to level 99 so early as it is not neccasary and you can complete the game easier and also you wont have much materia by then so if you want to get that high early make sure you have some cure,fire,ice and bolt materias as soon as possible then train or you will have good everything apart from magic and materia.but it is far from impoosible to get to level 99 at the start.