I have an 8 gallon batch of APA that I split into a glass carboy and a corny keg (4 gallons each). I pitched into the carboy that night but waited alsmot five days before pitching into the corny (sealed with a keg charger).
I didn't plan to split the batch, but wanted to try two different yeasts and the LHBS was closed for two days and I didn' thave a chance to get more yeast for five days.
The first half of the batch was well on it's way to being done before I got to the second. The second half was pitched with Notty, which is really agressive. It seems to have caught up with the first and now they're both about finished and waiting for me to bottle ... when I have a chance.
No worries about holding off pitching as long as your sanitation is good and you sleal that sucker up so nothing gets in it.