It'll happen quite soon anyway. However, it will change things.
Colombus was extremely motivated to justify the investment in him. He massively overstated the amount of gold found, and his overstatement was widely publicized.
Colombus also discovered the Caribbean Islands first. To Europeans, they were land with low numbers of natives on most of them, and once seized, provided bases that the mainland empires simply could not reach.
Whats more, they provided direct access to the gold-rich empires of Mesoamerica, meaning Europeans were there at the same time as the disease-shock.
A discovery process without Colombus, most likely propagating from Brazil and North America, may involve a drawn-out period of low interest by European powers, until gold and other profitable materials are discovered.
It may also mean that the initial, most severe disease-shocks arrive well ahead of the Europeans, and the European themselves don't get to the empires until they have started to pick up the pieces. The Mesoamerians may also have some information on the Europeans from tribes that have met them by then.