I was at the 29th also for the Stage 1 assessments, had the same issue had a text on the 5th around 15:09 no email, it was followed up with another text and an email to book stage 2, whilst pricing trains and moving things around I booked the 13th trains but then when I clicked back to book the OPC day both the 13th and the 20th had gone off the list only the 16th left, was able to get on that day at the cost of 60quid more as the 06:03 train was more expensive than 13th/20th, I'd say no news is good news from how quick the stage 2 slots went as by 18:13 there was just the 16th left and the stage 2 email came at 16:12 so depending how many slots are allotted a day, that's fairly quick. so if you've heard not it maybe awaiting more available dates from the OPC.
Hope this helps