The notification of route is normally at the discretion of the examiner - you may well only get 1 hr to plan - a lot of times its done the day before so you can arrange for instrument slots which are a ****** to come by on the day itself after 8-9am...
And anyway...you proved you can do it already for the cpl!
1hour is plenty of time for planning - if you cant plan in 1 hour then I suggest you need more practice...certainly an IF route (simple) up to about 2-3hours can easily be done in 1 hour.
Hope it goes well for you though - good luck!
Let us know how you do!