The Morecambe super-lightweight prospect, 8-1 as a professional, takes on the durable Lee Connelly for a British Challenge Belt in Bolton on Saturday night.
Cornerman John Donaghy says his man is more than ready and will be looking to impress at the University of Bolton Stadium.
“Lee Connelly has cancelled a couple of fights to concentrate on this,” he said.
“He’s taking it seriously and it should be a good fight.
“For Reece it’s a potential banana skin but if he can’t past someone like Lee Connelly then he’s not going to go as far as he wants.
“He needs to be winning and winning pretty well.”
The 23-year-old is known for an all-action style and is set to be well backed by a growing following this weekend.
MacMillan has been working hard at Donaghy’s gym in Preston with his trainer pleased with how his fighter is developing.
“We’ve been working on some new stuff,” he said.
“I’m getting him to think a little bit more about what he’s doing.
“Sometimes he needs to step off and have a look before going on the attack.
“As you move through the levels fights do become more like chess matches.
“You can’t just steam in and throw punches all the time.”
Part of MacMillan’s preparation has seen him head to Marseille for sparring with popular Frenchman Renald Garrido, a familiar face to fight fans in the UK having fought several times on these shores.
It has served as the ideal build-up as the Skerton ABC man steps up to compete over eight rounds for the first time in the paid ranks.
“He went over sparring in France and did something like 18 rounds,” said Donaghy.
“It was organised by one of his sponsors and is a really good experience for him at this stage of his career.
“We’ve been going down to Manchester as well and he’s been doing eight rounds no problem, so that shouldn’t be an issue.
“Things have been going well, everything’s gone to plan and he’s ready.”
MacMillan’s 10th professional contest is part of the big ‘Risk vs Reward’ show being put together by his manager Kieran Farrell.