Within the first 30 minutes of ending the workout! The muscle is primed from exercise take up carbohydrate and amino acids at a maximal rate.
A quality recovery drink with 4:1 ratio of Carbohydrate to Protein is best.
I would suggest 1.5-2.0 grams CHO per kg body weight and .5 gram protein (whey) per kg body weight in recovery drink that contains 500-1000 mg sodium per liter. Add in some antioxidants vit C and E, some glutamine, and some BCAAs. That what the science says works!
THAT'S PROBABLY OPTIMAL BUT ONLY IF YOU CAN AFFORD ALL THAT
Products such as Endurox and Cliffshot recovery fit that bill. Powerbar Performance Recovery is also good, but lacks the antioxidants and glutamine.
GENERIC PRODUCTS WOULD BE CHEAPER, LOL. IF YOU CAN AFFORD THESE THOUGH GO FOR IT, WILL BE MORE CONVENIENT
Try to stay away from the stuff that adds 25 different kinds of UNPROVEN pixie dust compounds in it.
Follow up with a normal meal. Eat several small meals a day with bias toward complex whole grain carbohydates and SOME high quality animal protien.
fyi: Most of you weight training guys DO NOT require more than 2.0 grams of protein per kg of body weight per day to maintain a positive nitrogen balance! The excess protein is de-aminated and dumped into aerobic respiration pathways. The liver and kidneys must work over time to process the extra nitrogen from the amine groups...to excrete it as urea. If you disagree please find me the peer reviewed scientific studies that suggest very high levels of protein that is required by weight training athletes.
*YAWN* WHATEVER, BUD. TO EACH THEIR OWN. I'LL STICK WITH GAINING 30-40LBS A YEAR ON 2G PROTEIN, YOU STICK WITH WHAT YOU WANT.