How to get ready on time

Morning all - this is my first post, probably because I feel I should be able to deal with my childs autism on my own but this morning I am about to crack.  Bit of background, my 11 year old was diagnosed with autism last year.  She masks at school which means I get the full brunt of it when she returns,  That I can sort of cope with as I know it is coming.  What I  can't cope with is the mornings.  I get her and her sister up 1.5 hours before we need to leave to school.  Some mornings she wants to get dressed first (with me present the whole time) and other mornings it's breakfast first.  I have to constantly remind her to get up, get dressed, stop playing, eat your breakfast, do you teeth which gradually gets her more and more annoyed.  I can't leave her to it as she wants me with her all the time.  My other daughter is now suffering with the consequences as I cannot be there for her as well.  If I could just get my youngest to get herself ready on time without distraction my life would be 80% better and I wouldn't start work everyday feeling like the worst parent in the world.  I been on all the parenting courses and i've tried making her morning timetables, using egg timers to give her a set amount of time, I've tried making her laugh, shouting, staying silent, walking away. I even offered her money if she can be dressed by a certain time.  Whatever I do is wrong and not what she wants me to do .  When I ask what she wants me to do she says she doesn't know.  Is there anyone else out there having to deal with this every morning as I can't believe anyone else  would be stupid enough to put up with it as much as I do.  Sorry if this isn't the right forum for this but I don't know where else to turn.