Usually, on the trees I visit, the first few days of harvest are mostly small nuts (or those that haven't developed at all). It's as though the tree is rejecting the nuts that haven't developed properly (much like the "June drop" for apples). The bigger nuts usually fall a week or two later ... unless there's a significant wind in the meantime. Down here in "sunny" Jersey the small nuts have only just started to fall in the last few days, I'd expect to be able to collect worthwhile size nuts next week or the week after.