One thing to consider is the likelihood that the home will be done on schedule. Your lender cannot grant final loan approval until the appraiser does a final inspection and it’s underwritten. Many times builders seem to feel that the house just has to be done the closing date, in fact there’s a gap of several days on more in most cases. As far as locking, the only thing worse than locking too early (then seeing rates decline further) is adding the cost of a lock extension on due to construction delays. We seem to be firmly stuck in a rate range, I’m usually pretty lock oriented, but not as averse to floating as usual after two months of decreasing rates. 7 year arms can run about .375% below 30 year fixed rates, I’d price both out and decide if the savings justify the potential risk. Hope that helps.