Do you prefer to simultaneously start an ACEi/ARB and SGLT2i or initiate one prior to the other in a patient with proteinuria secondary to diabetic kidney disease?  

I would start ACE/ARB first. If, after 4-5 months the proteinuria is not within goal, then would add SGLT-2. Also, this will ensure that blood pressure does not drop too much.

I would almost always start one, see how things go, then consider another if needed. If hypertensive would start with an ACEI/ARB. I would want to see creatinine, K, BP before adding an SGLT-2i. If BP well controlled and not a lot of proteinuria, could consider SGLTi first.