The break in period for new burrs is a long process for home users as it takes many kg's. If the new burrs are particularly rough there may be some coarse adjustment immediately after purchase. Otherwise it will be a matter of minor adjustments over weeks and more likely months of time until the burrs are completely broken in.
Grinders are not 'set and forget' devices when used for espresso. As the temp and more importantly the humidity changes the grind setting will need to be adjusted. As the beans age the grind will need to be adjusted. If you use a different bag of coffee/change coffees you'll need to adjust the grind. If you use the same beans but from a different roasting session guess what. Yup. You'll need to adjust the grind setting.
Java "Change is normal" phile