For filegrowth, Yes - it won't effect the existing work till the next time when the filegrowth actually occurs. I would recommend though to avoid file-growth and to size your data, index and log files sufficiently large based on your requirements. You can always add more files depending upon your hardware and # of CPUs. The reason is that you do not want to incur the cost of filegrowth during peak production hours...so, monitor it and size the files accordingly.