In general, here is a typical scenario for your question:
1) In Pa., both county and local (municipality) taxes are considered "calender" taxes. Thus, If you settle on any property, say on June 30th, you'll pay, at closing, these taxes from that day until 12/31. Why, because these taxes are typically paid by the seller in early Spring. A quick eg.- Sellers' home has $1,200 annual county tax. He paid the bill in, approx., March. What he did was pay both backward, from jan. 1st, and forward, to 12/31. So, with a 6/30 settle....you'll pay 6 months of this tax, or $600, in essence paying back the seller for tax paid....your next bill will come next spring.
2) School tax is typically a "fiscal year" tax, running July 1 to June 30 of the next year. So...using the above settle date of 6/30...you essentially won't pay the seller back for any school tax. Why? At that day, the seller, if he/she is up to date, will only have paid through 6/30...the next bill, again paying back and forward, will be received in the fall (paying back from 7/1 through 6/30 of the following year. Now, in this scenario, a bit of a catch....YOU will be receiving the next school tax withing 2-3 months of settlement...and will owe from 7/1 through 6/30. So...the title agent, or settlement co., may require you to FUND your escrow account sufficiently, at settlement, to be able to draw those school taxes when they come due.....which leads to your question of escrow.
3) Escrow is what I call the dirty secret of lenders. At settlement, an escrow accout will be established with a certain amount of money. This money will be held by the lender and paid out as taxes, and insurance bills, come due (by the way, typically, you'll pay a full years' home insurance prior to settlement) As you begin to make your mortgage payments, a portion of all of your taxes and insurance, will be added to that payment (base payment being principal and interest). No interest is accrued for you to have the escrow acount sitting with the lender. The argument from them is that there are adminstrative costs associated with disbursing this money....O.K...
Finally, banking regulations allow only a certain amount of escrow to be held at settlement (I believe, but am not certain...14 mo.) To get a firm idea about ALL of the costs involved with your purchase, I urge you to contact a lender, get pre-approved through that lender, and provide details about the home you wish to purchase, including price, total taxes, any monthly recurring HOA (home owners' association, if applicable). Ask the lender for wht is know as a Good Faith Estimate, or GFE, for that property. He/she will provide definitive data for you to review...all at no charge or obligation (they do this to help them secure your business) Also, Realtors in Pa. are required to provide an estimated closing cost sheet to their buyers. As your Realtor for one. There are a lot of considerations aside from these I've outlined, but hopefully this will get you started.
Therefore,it really does not matter when you complete a closing. The adjustments will always be treated the same way. Does not matter if you are in Phila or Cheltenham townships. Proration of escrows will be the same. The only way to keep closing cost at a lowest amount is to settle at the end of the month because of the interest on the mortgage to the 1st payment. This does not save you one penny but would allow you to have less funds needed for closing but then the first mortgage payment would start 30 days after the date of settlement..