I personally never let my espresso blend "hit the hopper" until day 4 after roasting/bagging. I time out my roasts and delivery dates to make sure that this holds true for all of my wholesale accounts, ensuring that the espresso is always being utilized between days 4 - 11. If, for some reason, an account is going to be needing to get into the espresso before day 4, I'll let it off-gas in the barrel (instead of immediately bagging in foil bags w/ one-way valves), as this allows them to de-gas a bit quicker. The degree that a coffee needs to degas seems to be directly related to the origins, degree of roast, and time of the roast - or the overall bean density of the finished product.
My espresso blend is currently constituted of four different origins, roasted to slightly different degrees of darkness, and I've recently begun experimenting with off-gasing them individually to find their unique "sweet spots" - with the idea that each origin will have differing target dates. Hopefully then I can time out by roasting and blending to where each origin is reaching their peak at the same time. We'll see!
Definitely, it's been my experience that coffee that is too fresh produces a gassy, sharp (acidic), and rather flat shot lacking depth and complexity. Proper ageing seems to smooth out the edges and marry the flavors as designed. An espresso that has just passed it's peak may actually be smoother yet, but one will notice the crema dissipating too quickly and a diminishing of it's defining characteristics. Experiment! Thank God none of us hold all the right answers, as we may then become (shudder) bored. And wonderful forums like this would no longer be needed.