A first birthday is really two photography jobs, and treating it as one is the most common way families end up disappointed with both.
The studio session
A few weeks ahead, on a themed set. This is where the invitation image comes from, and the framed print, and the photograph that goes on the wall. It is calm, it is controlled, and the child is not surrounded by forty relatives.
Book it at least three weeks before the party if you are printing invitations, and four to five if you are posting them. Printing consistently takes longer than everybody assumes.
The party
Documentary work in a room full of people. Arrival, the rituals, the cake, the guests, the grandparents watching. It is a completely different discipline from studio work and it produces a completely different kind of photograph — the ones you will actually look through in ten years.
The twenty minutes that matter
Do the family group photographs within the first hour. Before the child is overwhelmed, before the cake, before half the relatives have drifted outside to take a call.
Every family that leaves the groups until the end spends the last part of the party chasing people around a car park, and the resulting set has gaps in it. Give us twenty minutes early and you get a complete record: the whole group, each side of the family, each couple, the grandparents with the birthday child.
How many photographers
One is fine up to roughly seventy-five guests. Above that, a single photographer is always in the wrong room at some point, and coverage develops holes that nothing fixes afterwards.
What you get, and when
A curated highlight set within 72 hours — while everyone is still talking about the day — and the full gallery within three weeks.