Round where I live the cabinets were switched over to the new ones around the end of April start of May. At the time the checker had an estimated date of end of June. The next town over by about 3 miles had the "Not currently in rollout plans" showing. Last week, the checker updates to show that my town gets pushed another quarter to the end of Sept and that next town over suddenly gets switched to "Accepting Orders".
So, if you've only just got the new cabinets installed within the last week or so then there's still quite a while to go yet before you will be able to place an order. Hopefully it won't be as long a wait as mine has (so far) turned out to be.
Anyway, if you've not seen the "new" site the Open Reach people are using to "announce" exchanges then click this...
...as tweeted by them last week...
Not sure if they're still using the twitter account to announce or not as nothing new has appeared since that site posting.