The midfielder, recovered from a knee injury, is due to return to full training next week but Wenger will be patient with him.
"Diaby is coming back now," he said. "He had a preparation in France, where he had his rehab, and will be back to full training on April 1.
"Let's not forget he has not played for a year. I cannot predict now how much time it will take him to be competitive.
"I cannot plan for him to play a role now in the coming games, but maybe I will have a good surprise when I see him."
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