@Stormcrownn @YamiZetsumei You can unlock Samurai and Red Mage as early as level 50; It's unclear if A Realm Reborn needs to be completed fully to gain access , but it'll definitely call for the initial batch of main scenario quests to have been conquered at the very least.
Your character's race plays a very minor role in statistical progression and gender has zero effect whatsoever, so I wouldn't bother trying to go for an optimal setup. Feel free to pick whatever combination you find most agreeable to your tastes.
As for the jump potions being introduced: the main scenario option will only complete the quests necessary to access Stormblood's content, thus should you be lacking a level 60 Job, it's essentially useless and must be paired with the other potion to properly be utilized. The combined total will be $50 all said and done, however, if you're a new player and in no real rush to play with veterans in the most relevant content, I strongly recommend you avoid both options and engage the game as properly intended.