The free transfer duo are yet to make their Baggies bows having arrived, in Kelly's case, on deadline day and then after the closing of the window for Rogic.
Exciting Australia international Rogic, 29, arrived with big pedigree having shone for almost a decade north of the border with Celtic, where he collected a mammoth trophy haul.
Attacking midfield schemer Rogic was a big hit with the Hoops fans and it is thought the club are excited about the impact he could have. Both have been training with the squad during the two-week international break and Bruce admits Albion are feeling positive about the creator's potential impact.
Bruce said: "Out there the consensus is 'how have we managed to pull that one off?'
"He's ready, he's ready to go. I'm sure he'll have a big influence for us, he's a big player who's played at the highest level so we're expecting good things from him.
"It's (the break) given me the time to put in the work for Rogic and Kelly, so it's been good in that respect.
"That's been the key to it – they've been here another two or three weeks and they've put in a lot of physical work. They've both sort of had a mini pre-season, so they're ready to go.
"They're both very experienced, they've both played at the top level, they'll be decent acquisitions for us."
Experienced defender Kelly, 32, meanwhile, has played little football for previous club Crystal Palace in recent years but was recruited given availability issues in the backline, notably the injured Semi Ajayi.
Albion host 16th-placed Swansea tomorrow desperate to improve on a record of one league win in 10 this term that leaves the manager under pressure with the Baggies down in 21st.