While I agree a month end close is cleanest, you still must have a mechanism for the post-close net working capital true-up. The swings in working capital can be substantial, and the last thing you need is a surprise at how much "more" you're going to have to invest to keep the lights on while you collect what you originally expected. A transaction-oriented attorney and accountant should help you think this through.

Some good points above, but many are way off.
I teach this subject. In all my deals over 30+ years, the NWC and the language of the LOI is such that the Closing can occur on any day of the month w/o impacting the seller or the buyer. Also, the text removes any motivation by seller to manage NWC.
NWC is calculated to be $145 k. I am assuming Price includes you receiving NWC. If AR is low on the day of Closing, then NWC at Closing will be less than $145 k by, say $X. In this case you will reduce the cash to seller at Closing by $X. Your financing will not, should not, change. This will increase the cash on your opening balance sheet by $X which will help fund as AR gets back to normal. If closing NWC is higher the target NWC of $145 k, you need additional funding (bank, LOC, or short-term seller financing).
You need post-close true-up.
happy to talk.