The end of 2024 is the most likely time for the start of negotiations between Russia and Ukraine. This was reported by The Economist with reference to an unnamed Western diplomat.

The peace conference on Ukraine in Switzerland, scheduled for June 15-16, is unlikely to silence the guns, and serious negotiations are unlikely to begin before the end of this year, the publication notes.
According to a Western diplomat, there are several factors that determine the timing and conditions of a ceasefire in Ukraine.
First, it will depend on the state of affairs at the front: if Ukraine can hold its ground after Russia’s summer offensive, it will be in a stronger negotiating position.
Secondly, it depends on the state of health of Russian President Vladimir Putin.
Third, it also depends on the US presidential election in November.
So, the diplomat said, the end of this year is the earliest foreseeable date for negotiations to begin, and possibly much later.