The SPL clubs were in unanimous agreement two weeks ago on pushing for a merger with the Scottish Football League and the introduction of top-flight play-offs and Gilmour was happy with the continuing consensus on Monday.
On his way out of the Hampden talks, Gilmour said: "I think we'll vote very soon. It could well be (this week). We agreed we can take a short notice (vote). Then it's up to the SFL clubs to make their decision."
The 30 SFL clubs were also in unanimous agreement on Friday but they came up with a different model of governance and wealth distribution.
SFL clubs want money going from First Division clubs to the two divisions below, which could affect SPL clubs' views given they want a softer landing for relegated teams in return for opening themselves up to a greater chance of relegation via a play-off.
Gilmour would not expand on the differences between the two proposals but he was satisfied with the SPL discussions and believes change remains possible this summer.
"I think it's the right thing for all 42 clubs," he said. "It's in the hands of the SFL clubs. We all have little issues but we have a middle road. We looked at the whole model and we're quite happy with what we've done.
"There has been exceptionally good compromise in the SPL. It's not exactly what the board of St Mirren would wish for but we are more than comfortable."
SPL chief executive Neil Doncaster is expected to give a more detailed update on the discussions following a board meeting on Monday afternoon.
The play-offs would involve the 11th-placed club in the top flight and three second-tier teams. SFL clubs would likely be given 14 days notice of a formal vote, which would follow any SPL vote.