  We study the initial evolution of the coffee ring that is formed by the
evaporation of a thin, axisymmetric, surface tension-dominated droplet
containing a dilute solute. When the solutal P\'{e}clet number is large, we
show that diffusion close to the droplet contact line controls the coffee-ring
structure in the initial stages of evaporation. We perform a systematic matched
asymptotic analysis for two evaporation models -- a simple, non-equilibrium,
one-sided model (in which the evaporative flux is taken to be constant across
the droplet surface) and a vapour-diffusion limited model (in which the
evaporative flux is singular at the contact line) -- valid during the early
stages in which the solute remains dilute. We call this the `nascent coffee
ring' and describe the evolution of its features, including the size and
location of the peak concentration and a measure of the width of the ring.
Moreover, we use the asymptotic results to investigate when the assumption of a
dilute solute breaks down and the effects of finite particle size and jamming
are expected to become important. In particular, we illustrate the limited
validity of this model in the diffusive evaporative flux regime.
