Practical Period End Date brought forward for early completers?

I'm not sure what is it you're actually asking. Where is the practical period end date you're thinking you might have to update? When someone finishes you populate the learning actual end date, but there's no requirement for you to revise any planned dates. 

If the apprentice is taking longer to complete, the duration (practical period) needs to be extended and the Apprenticeship Agreement and Training Plan updated with the new date, then re-signed. If an apprentice completes early does the practical period date in the Apprenticeship Agreement and Training Plan need to be brought forward with the new date, then re-signed?

No, you wouldn't need to. The point of extending those agreements (particularly the apprenticeship agreement) is that they should be in place for at least the full duration of the programme (see below):

We have clarified that the apprenticeship agreement must cover the actual duration of the apprenticeship (e.g. if the apprenticeship is extended, the apprenticeship agreement must also be extended). 

In the case of someone completing early, those agreements still cover the actual duration, but just a bit more besides. If you wanted to note their early completion on the training plan you could, if you felt so inclined, but the planned end date/s remain as they were. 

That's great to know, thanks for your help and clarification.