The Pischai Tchuvos in Even Ezer is only related to getting married before 18. Since the Mechaber says that its better from the Bar Mitzva, the Pischai Tchuve says that in our days people are weaker and they should not consider Shidduchim from the Bar Mitzve. But Chas Ve`Sholom to say that the Pischai Tchuve allows the Goyishkeit of delaying till 23.
Chu VeNoshuvo El hashem, & start younger.
Lman Bnos Yisroel