The Mishnah says that the Raban Gamliel said Krias shema when he got married. His talmidim asked him that "You yourself said , "Chosson Patur M`Krias Shema!"
It`s Mashma that he had Talmidim when he was a Bachur. Or perhaps from the next Mishnah which says Rachatz B`lel Shemaysa ishto it`s mashmah that this may be his 2nd marriage. I was wondering if one can be Midayek from here that there is a P`tur of Oysek B`mitzvah Patur min hamitzvah even on the 2nd marriage(does he still have Tirda B`machsheves Mitzvah)? Also I find it interesting that Raban Gamliel possibly had Talmidim when he was a buchur.
dov, Far Rockaway
Your question slipped through the cracks, and so we apologize for the delay in responding.
About having Talmidim while not married, I have nothing to add.
Concerning if there is Tirdah in his second marriage, if Tirdah is considered not knowing well about the act of Bi'ah, then apparently it should not apply. However, the Shitah Yeshanah in Kesuvos 6b explains according to Rashi that even a Baki in the act is still worried about what will happen.
The Rambam in Perush ha'Mishnayos learns that he is worried he will not find Besulim, and that applies also to his second marriage.
Rabeinu Yonah learns that he is worried that the act will injure him and cause him to become a Kerus Shafchah.
See also Yalkut Bi'urim of the Mesivta edition of Berachos (16a, DH Sibas Tirdas).
All the best,