Actually, he did stick rocks to a chasm wall as a bridgeman. The first time he notices himself doing this (accidentally) is sticking a bag to the side of a barrel in chapter 57 of WoK ("Teft tells him that he’s been consuming Stormlight, and Kaladin notices that he stuck a pack to the side of the barrel, where it is still hanging." from the TOR re-read at https://www.tor.com/2014/02/13/the-way-of-kings-reread-chapter-57/). Then, he starts sticking rocks to the side of a chasm wall in chapter 59 ("Kaladin realizes the solution, and begins Lashing rocks to the chasm wall." from the re-read summary at https://www.tor.com/2014/02/27/the-way-of-kings-reread-chapter-59/ - this is the same chapter that Hashal tells Bridge 4 that they are now assigned to permanent bridge duty and also chasm duty and shortly before he puts on the Parshendi armor for the first time on a bridge run). While this isn't very early in his bridgeman days, all of his bridgeman days were early in his time using radiant powers, so it's still valid.
