I like working with someone who has initiative, wants to do a good job and is keen to contribute to the team, but is there a time when initiative is not a good thing?
Sometimes a new person will want to contribute to the team and show their new employer that they have initiative so they will dive into something that they don't have quite enough information about yet. If you are a new hire, take the time to learn and ask questions. Your new employer is not expecting you to know everything right away and it is in everyone's best interest that you proceed cautiously at first until you know the ropes.
I always feel more confident when a new hire asks me a question and gets all the information before proceeding. I don't see it as a weakness, but as a strength. Of course there will come a time when questions about certain things will not have to be asked as it is hoped the new hire will catch on to the office procedures and their initiative will kick in and they will take on these tasks on their own, but in the beginning please ask.
A colleague and I were discussing this very thing as we have seen it time and time again with new hires trying to succeed and who end up making some avoidable mistakes by jumping in too quickly and making decisions before having enough information. The first months on the job are a learning and growing experience. Take advantage of this time to learn as much as you can and ask, ask, ask.