A few points to remember

The following are some noteworthy points about Flow design:

• As far as possible, use fewer elements in your Flow, so it will take less execution time.
• The limit on the number of executed elements at runtime is 2,000.
• One organization can have a maximum of 500 active Flows and processes.
• One organization can have a maximum of 1,000 Flows and processes.
• The date must be in MM/DD/YYYY format, and the date and time must be in MM/DD/YYYY HH:SS format.
• The Flow will return null at runtime if you leave any field or resource value blank.
• For a text value, if you want it to be treated as an empty string instead of null, then set it to {!$GlobalConstant.EmptyString}.
• At runtime, the date/time values reflect the time zone settings in Salesforce. For the running users and in the Flow designer, the date/time values reflect the time zone set on your computer.
• UTF-8 encoding for text in user input fields...