Does it really matter?
This may sound obvious but don't do it if it doesn't really matter! In some situations you may have bigger change on the horizon that will include the issue you are currently considering. Wait a while and do it all together. However if it needs to be done now then do it. The worst thing that you could do is leave it and the issue build up and then feel to big to change or address. Some things need to be challenged sooner rather than later.
Can you afford not too?
If you don't make the call, what will the impact be. Even if it doesn't work at least you can learn from it and make it better next time.
Matt