What to wear on a first day at a new workplace
On a first day, you may know the dress code but not the room temperature, the walking route or how formal the team feels. Pick a familiar base within the stated expectations and use a removable layer to give yourself room to adapt after you arrive.
Work with evidence you have
Check the welcome note or ask the contact who organized your start if expectations are unclear. A simple shirt or knit, tidy trousers and comfortable closed shoes are a starting point in many informal offices. Use a jacket if the workplace calls for more structure. If there is a uniform, protective clothing or a footwear policy, start with that requirement and build around it.
Plan for a longer day than expected
Wear shoes you have already walked in; building tours and new routes can add time on your feet. Choose a bag that holds any documents and the layer you might remove. A matching set can look considered, but make sure the base still works on its own in a warm office. Avoid bringing a piece you need to adjust whenever you stand.
Prepare two versions the night before
Lay out the same base with and without the jacket. Try both with the actual bag, then sit down. Choose the more appropriate version for arrival and take note of what people wear after you have been there. Update the outfit for the next day using what you saw.