its hard to do both man, but you got a gd split, however if i was you i would split up your arm session and incorporate them seperately and have another day off so your muscles have longer to rest and get bigger.
best thing really before a workout is a good source of carbs like an apple 45 mins before thats what i do and then a
100% whey isolate also at the same time, after training you can induce your body with some fast carbs straight away, with a high glycogen index and then 45 mins to an hour later have your protein shake, also with your shakes make sure theres not a lot of carbs, its more expensive but well worth it while cutting down,
bless