Please don’t listen to theprof1. Clearly he is complelty frei since after aleinu every siddur has the ani maamins and shiesh zechiros therefore they must be integral parts of shacharis too I’m not sure why he indicates it would be ever ok to skip it.
Besides, that the shulchan aruch DOES NOT say when “shacharis starts” nor does it say to say kitores
Please stick with DY and Feivel.