Good info here:
Fantastic study on the post-workout anabolic window (and how overhyped it is)
“Despite claims that immediate post-exercise nutritional intake is essential to maximize hypertrophic gains, evidence-based support for such an “anabolic window of opportunity” is far from definitive. The hypothesis is based largely on the pre-supposition that training is carried out in a fasted state. During fasted exercise, a concomitant increase in muscle protein breakdown causes the pre-exercise net negative amino acid balance to persist in the post-exercise period despite training-induced increases in muscle protein synthesis . Thus, in the case of resistance training after an overnight fast, it would make sense to provide immediate nutritional intervention–ideally in the form of a combination of protein and carbohydrate–for the purposes of promoting muscle protein synthesis and reducing proteolysis, thereby switching a net catabolic state into an anabolic one. Over a chronic period, this tactic could conceivably lead cumulatively to an increased rate of gains in muscle mass.”
"he primary takeaway from the research is that you don’t need to worry about slamming a protein shake the moment you finish training. It’s okay to chill out for bit, do what you need to do, and then consume your nutrients.
We estimate that there is approximately a 4 to 6 hour window in and around the workout. The specific timing ultimately depends on when you have a meal prior to training.
Thus, the closer your meal to the training bout, the longer the window following the session. Now there certainly is nothing wrong with consuming nutrients immediately after training. And the limitations of current research leave open the possibility that there may be a small but significant that could be meaningful if your goal is absolute maximization of muscle mass."