First off welcome to the dungeon,
Thats a good question, if you really want to mix them (remember you dont have to)
Morning and post workout 75% whey 25%
casein
Before bed 75% casein 25% whey
Any other meal 50/50 maybe
Theres no real definte answer to this thats just my recommendation,
Studies have shown that some casein mixed in with you PWO shake has many benefitial effects,
Bed time, gives you a small amount of whey and some casein to carry you over,
Sorta like homemade
syntha-6 eh? lol
Just take note of my earlier point "remember you dont
have to mix them