The Southend midfielder had been expected to be officially unveiled last night after completing the final phase of his medical in South Yorkshire.
Although an announcement failed to materialise, Wilder insisted there is no cause for alarm and is now pressing ahead with trying to finalise deals for two more players ahead of Friday’s derby against Sheffield Wednesday.
“We’ll try and get the maximum out of what we’ve got,” he said. “I keep saying, I think this is a really great club to join and hopefully we can get some more things done. If you speak to the lads who are already here, I think they’ll tell you this is a really good place to be.”
United, who have been drawn at home to Preston in the fourth round of the FA Cup, agreed a fee for Leonard last week having first expressed their interest in the 25-year-old during the close season.
“As far as I’m concerned, it’s done,” Wilder said. “He adds to what we’ve got here which is a great attitude, athleticism and he’s a really good player. We’ve worked extremely hard to get him and we’re chasing (others). We need to. I’ve made that perfectly clear.”
“It’s not taken too long,” Wilder, whose side are seventh in the table, added. “It’s only been two windows.”