The Amazon website normally shows DVD release dates several months in advance (often with the chance to pre-order) but NCIS Series 13 isn't currently shown on either Amazon UK or Amazon USA (where it might well appear first). So it seems unlikely that Series 13 is due for release on DVD before, say, April (and possibly quite some time after that).
With the rise in online viewing, many major TV series (particularly from the USA) are likely to be offered on a streaming basis before they're transferred to DVD. (Those in the USA can watch each episode of NCIS Series 13 for $2.99 or the whole series for $39.99). It's only when revenue from streaming services dries up that the programmes will then be offered on DVD.