There are many types of building inspections and contingency inspections for homes which are traditionally done once a Purchase and Sale offer has been accepted by a seller - General Building, Chimney, Water Quality, Quantity, Air Quality, Zoning, etc, In the purchase and sale offer a buyer will specify the number of business days (often 7-15) to complete the inspections and negotiate any contingency amendments to the offer. It is important to get the inspections completed ASAP to allow time to get results of certain tests (such as Water or Air Quality) so that your agent has time to negotiate adjustments to the offer.
You may also bring in professionals before an offer is submitted -for example - if you suspect a an old snowman type furnace might want to be replaced - you might consult a heating specialist to get an estimate
that you might use to negotiate a better price, or to ask for escrows from the closing to be used for replacement of the system. Inspections are paid for by the purchaser. They are necessary so that home buyers know what they are getting into for possible repair costs before purchasing a home and also can be an eye opener to the fact that you might be getting in over your head and are a way you can get out of an offer should immediate repairs be to much to handle. Time is of the essence.

Ok... I will chime in on the inspector side of things. Once in a while we will do a home prior to an offer or an acceptance but I always warn clients, I may do this today and someone else may make an offer tonight before you get the report tomorrow to make your offer... thus losing out on the home and spending the inspection fee for ultimately nothing. We generally email all our reports to speed up the process but hard copies are always available.

just pay for the stupid thing already im gonna be cold soon

Of course I agree with the answers below. I had my inspection done almost immediately after the accepted offer so that we could negotiate the fixes. The inspector sent me a bill with a very thorough report in a nice folder (I was in another state) and I mailed a check.

I would have to wonder ... if a house is very old or in questionable condition, someone might want to invest in an inspection prior to making an offer. I've seen many real estate ads that say, like "sold as is - inspections welcome".

Hi T.A.B. - I'll chime in with one more suggestion: Once you have an accepted offer (signed contract), order the inspection right away. The Purchase & Sale Agreement (contract) will specify the number of days that you have to conduct inspections. The days indicated are business days, not calendar days. While each contract is different, many Sellers don't like the inspection period to go past 10 business days, which is two calendar weeks. But if the inspection finds an issue, further inspection or negotiations might be necessary and the intent is to resolve inspection issues, not just find them, within the specified number of business days.
So your best bet is to order the inspection immediately after getting a signed contract.
Good luck!
Margaret

Inspections are generally done after the offer has been accepted. There will be a time limit for getting them done. During this time you can cancel the agreement or negotiate the cost of repairs with the seller if the inspection doesn't come out to your liking.
It is up to the buyer to hire and pay the inspectors. They generally like to be paid at the time of the inspection.

Usually you do the inspection after the offer has been accepted. That way you are not paying for something that you might not own. Most inspectors like their money the day they do the inspection.