"It's really tough with concussions to name a date because that puts pressure on the player and they feel like they're letting people down if they don't make that date," MacDonald said.
"He won't be around the first round and what happens after that, fingers crossed we start seeing him around the team and potentially available. The first round is definitely a no go for Beauden.
"He ran pretty well today and is getting into some high-intensity training. He's feeling really good, his energy is good. Once he gets inside the Queenstown bubble and starts talking rugby it will be hard to pull him back."
In Barrett's initial absence MacDonald will be left with a choice between Auckland's Harry Plummer and Stephen Perofeta, last year's NPC player of the year from fullback for Taranaki, for the starting first five-eighth role after Otere Black's departure to Japan.
The Blues will also be without All Blacks prop Karl Tu'inukuafe for the first two months of the season after he underwent minor back surgery in December. The injury was initially expected to sideline Tu'inukuafe for the entire season but he is now on track for an April return.
"Karl was running today, albeit slowly, but that was his first time on the grass and we weren't expecting to see that for a long time," MacDonald said.