Mine was same Howler, got the text it was despatched by HMPO last Tuesday but took nearly a week for anything to appear on TNT then boom, I tried last night at 6pm and it let me in to see tracking.
Annoyingly there is no rhyme or reason to this – it really does seem to be luck of the draw – I got the printed text yesterday from HMPO and within an hour tracking was on the TNT site, out for delivery today.