Bangladesh's strength and conditioning coach Mario Villavarayan has said it would take Mustafizur Rahman four weeks to be fully fit.
When asked about a time-frame of his recovery, Villavarayan said his improvement will be assessed every week and recovery could be complete in the next four weeks.
“Ideal [time to be fully fit] would be one month,” Villavarayan said. “But we will see how he does this week and take it from there.
“As of today, there's marginal improvement. It was a long season for him, so we are working on him. We assessed him yesterday and he has improved, and we will assess him again next week and take it from there. He has responded well.”
Mustafizur, who has already missed four Royal London Cup and five NatWest Twenty20 Blast matches for Sussex, will be unavailable for another six T20s and the rest of the one-day tournament. He would then be available for three T20 games in the end of July, unless Sussex progress to the next stage in both competitions.
Last month while playing the Indian Premier League, Mustafizur informed some of his close ones in Dhaka that he was getting tired which prompted Sussex to give him some leeway in his contract, at least up to June 10.
Last week, Bangladesh's physio Bayjidul Islam said he would be assessed for the upcoming two weeks before any decision is taken on his stint with Sussex.
