The general workflow for designers in a product development team,is to discuss ideas and concepts, then sketch them on paper, then perhaps produce a higher-fidelity visual using Sketch, before creating the interaction points using something like Invision.
Jones Downey, in his post Writing first Design, introduces the notion of writing before you sketch, providing designers with the opportunity to convey the narrative earlier on, without having to wait for the sketching to be completed.
This affirms any misunderstandings, and allows for greater collaboration and transparency, not just within the design team, but to also allow for feedback from test users but from product managers and project leads.
You design-by-writing, by creating communication actions, as the blog post author Jones Downey articulates, copywriting that can be prompts, labels, mocking basic UI in text:
We need access to your location, in order to provide you with the best food delivery services. Will you grant us accessories <YES> <NO>
You can use angle brackets to symbolise buttons for instance. Another example of a communication action could be a screen to register a new user:
**Step 1- register with Facebook or enter your email and password below** <Login with Facebook> or Email: <email address> Password: <password>
You can create workflows to point where one goes to another , by drawling lines and showing variations in paths based on user actions. If the user selected Facebook above, the next step would be:
**Step 2.1 - Confirm your photo/ avatar** <Photo Avatar>
taken from a great article on A shorthand for designing UI flows
Once your narrative and UI flows are mapped out in writing, you can go through the workflow with the appropriate project team stakeholders, for the critical early-validation, before committing to the prototyping and other fidelity tasks that will take more time. The goal is to engage customers and product owners earlier on , and designing by writing is the quickest most logical way in my opinion.