Optimal rotation for dps brant ?

I have him at 258 % ER. When i start with my team, i use his echo and then swap to SK and then to sanhua and then to him with his ult and then BA hold + 3x BA and then forte.

The main problem is that when i switch to SK it takes an insane amount of time to get her concerto full ( i am probably not proc’ing her intro, is that the problem ? ), sanhua is fine but the 2nd problem is that when i switch to brant finally, his ult is just like 1 or 2% away from being able to be used. How do i fix it ? Thnx.