In this work we carry out theoretical study of the formation of an In wetting layer on the surface of As-stabilized GaAs(001)-(1×1) to better understand the growth kinetics of metal droplets during droplet epitaxy. For this study, we calculate the dependence of the adatom adsorption energy (Eads) on the In coverage, since its value describes force with which adatoms interact with substrates, directly affecting their mobility. Calculations were performed using the state-of-the-art approaches of the density functional theory. The results show that at 0.125 ML coverage Eads has very high value of 8.48 eV which is explained by the adsorbate induced surface reconstruction being included in calculated value. With increasing coverage Eads dropped significantly (down to 3.588 eV/adatom at 1.75 ML coverage) which can lead to subsequent adatoms having greater mobility and can affect the size and surface density of metal nanodroplets and quantum dots based on them.