Quick answer

Use day one for the historic peninsula, day two for Galata/Karakoy/Beyoglu plus an evening area, and day three for ferry time, Kadikoy or Uskudar, and a slower food or Bosphorus layer.

A simple first itinerary

This is not a minute-by-minute route. It is a structure that keeps the city from feeling scattered.

Day one should stay near the old city and major monuments. Day two can connect Galata, Karakoy, and Beyoglu with food and evening time. Day three should use water: a ferry, a Bosphorus view, Kadikoy, Uskudar, or a slower neighborhood plan. Add museums or hammams when weather or energy calls for it.

Planning Choices

Day 1
Historic peninsula cluster. Start early and keep the day close together.
Day 2
Galata, Karakoy, Beyoglu, and evening food. Use walking plus short transit links.
Day 3
Ferry, Asian side, Bosphorus, or slower neighborhood time. Choose based on weather and energy.