To add to the excellent 50 mile oil change recommendation I suggest:

Use a universal grade oil which has more detergent additives to deal with soot dispersal, these are formulated especially for diesels. Examples are: Chevron Delo Multigrade, Mobil Delvac, Mobil Delvac One and Shell Rotella T.

Ensure that the oil is at operating temperature(minimum of about 17 miles driving) when you pull the drain plug. This will ensure that the sludge is churned up in the oil so it will come out, and it will be thinner allowing more oil to come out.

Drain overnight if possible, this will get every last bit of sludge out that can come out.

Good luck,