According to my model Venus achieves its greatest brilliance for its current evening apparition at magnitude -4.5 on April 29. In reality subtle shifts in Venus’ atmosphere can slightly alter the accuracy of this estimate. Venus stellar magnitude is essentially stable around this value for a couple of weeks before April 29 and a week or so afterward.
Venus’ brightness has been slowly increasing since superior conjunction in August. Its growing angular diameter has compensated for the shrinking fraction of disk illumination (phase). But now the latter factor will become dominant. There will be a somewhat noticeable drop off in brightness from mid-May into the early June transit when Venus will appear as a black dot on the Sun.
Below is a graph I created to chart the changes in Venus’ brilliance. For more of my related Venus graphics including transit previews for 44 cities, check out my Venus webpage: www.CurtRenz.com/venus