I work at a web development agency. For the 8 months I've been here, we've only built simple HTML websites for local businesses in our area. I don't feel like I am growing professionally and doing mickey mouse jobs. Will it affect my future opportunities if I leave before the 1 year mark? I just don't want to waste anymore time.
If you're asking this question, then it's already not early enough. You should've started making plans to leave once you realized you weren't growing professionally. As long as you have a valid reason (which you do) to explain this move to future employers, then this shouldn't affect your opportunities.
Agreed, you can also seek out opportunities for additional projects or positions internally as a route for career development. If you've proven your skillset as a developer and your boss sees it, it should be easy to have this conversation since you're too good for this job. If you're more of a junior developer, pursue opportunities as a lead developer. If you're in more of a test role, try switching to dev, and vice versa. Even the same type of position at a different department or team can be a challenge in your career.