Juanjo will begin his Bradford City life on the bench at Crewe tomorrow night. City boss Jim Jefferies is keen not to push his new recruit too quickly by starting him in the televised clash.
Juanjo is well used to being a substitute under Jefferies - 34 of his 45 games for him at Hearts were from the bench.
Jefferies said: "I don't want people expecting miracles straight away. Juanjo has the ability to change games but we will ease him in gradually.
"We're trying to build a squad with a bit of pace about the side and he is a big part of that. Juanjo's best years are still ahead of him but I don't want to expect too much too soon.
"He took a while to settle at Hearts which was not surprising coming from the type of football he was used to in Spain. He became a bit frustrated at being held back but the potential was there when I unleashed him in my last year.
"Obviously he was younger then, but like when Gary Locke came down here he will need a run of games to get used to it.
"Once he does settle then the supporters will see he has got great ability, can cross a ball and comes up with the odd goal out of nothing."
Juanjo played the full game for the reserves last night in their 2-1 defeat to Newcastle after Hearts agreed to cancel his contract a day early.
He said: "It would be nice to get the chance to play straight away for the first team and be in the Crewe match.
"People are always talking about Scottish football and saying it is not good enough and doesn't compare with England - that's why I want to show I can do just as well down here.
"The fans are expecting a lot from me and I hope I can make a difference for the team. I'm a fast guy who likes to put the ball into spaces and get crosses over or take defenders on.
"The Hearts supporters really love me because of the way I express myself on the pitch with my somersaults when I celebrate a goal and the way I laugh during the game.
"People connect with that and I'm sure I can have the same feeling from the fans here."
Locke is convinced his former Jambo pal will be a big hit. He said: "The English First Division will suit Juanjo better than the Scottish Premier with more time on the ball.
"Friends in Edinburgh tell me he's probably playing the best of his career so it's a great signing for Bradford."
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