You can use the following storage sizing guidelines as best practices.
Size the deployment with twelve to eighteen months of infrastructure growth
When an environment outgrows the original deployment size, performance degradation and usability problems may become present. Planning for infrastructure growth of twelve to eighteen months will allow the system to continue functioning without the need to immediately resize or scale out the deployment. For example, if you anticipate a 10% annual growth, increase the initial sizing by 15% to obtain an eighteen-month sizing recommendation.
Review the sizing guidelines frequently and often during the growth of the environment (resizing)
To keep the environment running with optimal parameters, it is important to review the sizing guidelines and resize the deployment as necessary. Even with expected growth, frequently reviewing the sizing guidelines regularly will proactively prevent performance and usability problems typically associated with undersized environments.