You want those sleepy, curled-up newborn photos, but the window to take them happens in the first two weeks of life. That means you have to plan and book the session long before the baby actually arrives, usually right in the middle of your second trimester. Waiting until you are home from the hospital is simply too late to secure a good photographer.
A typical session runs about $450 in the US, and you need to know how that fits into your wider baby budget. By nailing down the timeline early, you can lock in your dates and handle the cost in manageable chunks instead of scrambling to pay all at once while adjusting to life with a newborn.
That 0% window is a deadline, not free money, so make sure the balance is completely paid off before the 18 months are up or standard interest rates will apply to what is left.