Commissioning of the plant started in late February and the company reported today that the semi-autogenous mill was ready for commissioning.
The first ore should be fed through the mill by the end of the month, with first gold to be poured about two weeks later.
"Commissioning of the plant by EPC contractor GR Engineering is now well advanced with the SAG mill, the single largest and most complex piece of equipment ready to go," Calidus managing director Dave Reeves said.
"We are confident of meeting our April milling timetable which will lead to first gold two weeks thereafter."
Reeves said mining contractor Macmahon Holdings had ramped up activities with the main mining fleet now in operation and 24-hour mining on schedule for later this week.
About 140,000 tonnes of ore is on the run-of-mine pad with a target of 200,000t for the start of operations.
Warrawoona is set to produce an average of 90,000 ounces of gold per annum - peaking at 105,000oz - over eight years, at all-in sustaining costs of A$1290 an ounce.
The project has a post-tax net present value of $245 million, internal rate of return of 57% and a 15-month payback period at a gold price of $2355/oz.
Warrawoona comprises one large low-strip open pit and an underground mine, as well as a conventional 2-2.5 million tonne per annum carbon-in-leach.
Calidus is also completing a definitive feasibility study on the nearby high-grade Blue Spec deposit, which could see production rise to 139,000ozpa.
The company has hedged an additional 20,000oz of gold at $2688/oz, for delivery this year.
Canaccord Genuity analyst Paul Howard noted that Calidus was already re-rating ahead of first production and was up by more than 50% so far this year.
"We believe Calidus continues to offer exposure to one of WA's next gold production stories and that it offers a low level of risk given the conservative nature of mining studies published to date," he said.
Howard maintained a speculative buy rating and $1.15 price target.