Hey there, i started a prophet alongside my main (tyrant) and had no issues, of course if you are planning to exp the prophet to the same level as your main you will have to grind more everyday, in comparison to level solo, but there are one thing u need to consider.
- Playing solo will get you to top levels faster (depends on the class ofc) but u will have to spend more adena to get you there.
- Playing with a prophet will make you to top levels slower, but in the long run you will save much more adena, with the addition of having a prophet that you can use to buff yourself during casual pvp, siege and to "secure" a spot on any raidboss groups that needs a high lvl prophet.
You dont have to level the prophet to 70+, you can keep the pp on lvl 58 and you are set to go.
Of course, having a CP since the begining might be more beneficial to you, you wont get bored so quickly, and overall youll have more fun. But i can understand that those cases are not for everybody, you can perfectly reach to top lvls and have fun your own way by playing solo.