  Solar active regions are associated with Evershed outflows in sunspot
penumbrae, moat outflows surrounding sunspots, and extended inflows surrounding
active regions. The latter have been identified on established active regions
by various methods. The evolution of these inflows and their dependence on
active region properties as well as their impact on the global magnetic field
are not yet understood. We aim to understand the evolution of the average
inflows around emerging active regions and to derive an empirical model for
these inflows. We analyze horizontal flows at the surface of the Sun using
local correlation tracking of solar granules observed in continuum images of
SDO/HMI. We measure average flows of a sample of 182 isolated active regions up
to seven days before and after their emergence onto the solar surface with a
cadence of 12 hours. We investigate the average inflow properties with respect
to active region characteristics of total flux and latitude. We fit a model to
these observed inflows for a quantitative analysis. We find that converging
flows of around $20$ to $30$ m/s are first visible one day prior to emergence,
in agreement with recent results. These converging flows are present
independently of active region properties of latitude or flux. We confirm a
recently found prograde flow of about $40$ m/s at the leading polarity during
emergence. We find that the time after emergence when the latitudinal inflows
increase in amplitude depends on the flux of the active region, ranging from
one to four days after emergence and increasing with flux. The largest extent
of the inflows is up to about $7 \pm 1^\circ$ away from the center of the
active region within the first six days after emergence. The inflow velocities
have amplitudes of about $50$ m/s.
