Novak said the contract with American partners is in its final stage and that further shipments will follow the first vessel.
Putin gave a different timeline several hours later, telling Trump's special envoy Steve Witkoff at a meeting that the first tankers would sail in two to three days.
Trump and Putin spoke by phone on October 9 and afterward announced an agreement on supplies of Russian diesel to the US and global markets. Trump said Russia would ship more than 300,000 tonnes immediately, another 500,000 tonnes in November, then one million and a further three million tonnes.
The US Treasury issued a temporary license allowing deliveries of Russian diesel to the global market in circumvention of sanctions. The Russian government partially lifted its ban on fuel exports from October 10. The restriction had been in force since the autumn, when Ukrainian strikes on oil refineries caused fuel shortages inside the country.
Novak indicated that Russia would not be able to reach the volumes promised by Trump quickly. Exports are recovering within the capacity of the refineries, and the full volume on schedule will be reached only by the end of the year, he said. Other countries will then be able to receive diesel in the previous volumes again.
Ukrainian President Volodymyr Zelensky called the Russia-US diesel deal an investment in the war.