Create different Jira groups for your Tempo needs according to your company. Then it's easy to add or remove users from these group as situations change: no need to grant permissions on an individual basis. Here are some suggestions:
All Tempo users - if only certain Jira users in your company need to use Tempo, create a group with only them in it. Then you can give access to Tempo Timesheets using this group.
Tempo administrators - high-level admins who have permissions to manage Tempo in your company.
Tempo Account administrators - admins and financial managers who will be creating and using accounts for billing and/or tracking Capex and Opex.
Tempo Team administrators - team leads and managers who will be creating and possibly managing teams in your company.
Tempo teams - create one Jira group for each team you plan on creating, or one group for each department. Then you can add all members to a team in one click using the Bulk AddMembers button - see Creating Tempo Teams.