Cassein you would want more during a main meal and an hour before exercise. Whey you would want with in 30 mins after exercising.
To some extent taking caseinate prior to a workout makes some sense. However, Dr John Ivy (Nutrient Timing) recommends whey combined with a high glycemic index food, like maltodextrin.
The whey/maltodextrin is ingested about 30 minutes prior to your workout.
Ivy goes on to recommend that you sip a whey/maltodextrin beverage during your workout as well.
Then within 15 minutes of finishing your workout, you ingest another whey/maltodextrin beverage.
This mixture spikes insulin levels. Insulin is show to be one of the most anabloic hormones there is.
Also, insulin has been shown to shut down cortisol production, which is catabolic.
A positive effect is evoked when you ingest a high glyceminc index food prior, during and after your workout.
Ingesting a high glyceminc index food outside of the workouot time frame creates a problem. While insulin is an anabolic hormone, it is also a "fat making" hormone.
As nutritionist Jay Robb once stated, "Insulin is a fat maker and glucaton (a counter hormone to insulin) is a fat taker.
When insulin levels are low, glucagon come "out of it's cage"...so to speak.
Insulin levels are lowered and glucagon is increased when low glycemic index foods/complex carbohydrates are consumed.
By learning to manipulate these hormones in a positive way we can maximize our muscle gain and decrease body fat.
It's like using the right tool for the right job.
I have used a crescent wrench to hammer a knock a nail into a board but a hammer works a lot better.