Whether one staggers carbohydrate consumption when supplementing with BCAAs (or any other amino acids for that matter) or not is probably of negligible significance. Amino acids are zwitterionic and act as pseudo-buffers, and consequently their digestion shouldn't be affected significantly by stomach pH (which would presumably be increased slightly by carbohydrate consumption). Furthermore, if I remember correctly, proteins and amino acids are digested by a largely separate set of enzymes than carbohydrates, so they won't be competing as substrates for enzymes' active sites. Also, carbohydrates are generally metabolized much more rapidly than proteins and amino acids in any case, so even if you ingest them simultaneously, you will metabolize the carbohydrates completely before you finish metabolizing the proteins or amino acids. Finally, I suspect there's probably little benefit to BCAA supplementation to begin with, but even if there is, the process of digestion is so complex and variable, and so dependent on a wide array of factors (e.g., circadian rhythms, genetic variation, medication usage, etc.), that investing time and energy into trying to micro-optimize supplementation timing is going to yield marginal returns, if any.