I preform many of both.
Which builder/how have things gone on the build?
If you are choosing one or the other, I would recommend before closing. Around the time they are ready for final walk through a week or two before closing.
Advantages before closing are:
You don't own the house yet. Worst case, you can still walk. Happened twice last year. Average one or two a year. Involves leaving a good amount of money on the table, so not done lightly.
You have better leverage on gray area items, though this is limited a little in the really hot markets where builders may not care as much.
Better to find things early if you can.
11 month is usually encouraged by the builder. Nothing wrong with doing an inspection then, I do lots. But at that point you own the house regardless. The builder also has a little more leverage regarding what they decide to warranty. /cover.
You may not need to do both. If it is a good builder and the first inspection is really clean and the year goes well, I would probably skip the second. But if things have been rough and major stuff comes up, a second inspection may be a good idea. I would say around 30 percent of my new construction clients have me back.