Since the thousands of worlds comprising the Imperium have different day lengths and orbital years, a standardized date system was established around a 365-day year with 24-hour days (convenient for those of us in the real world, right?). Although local and regional traditions and names persist in some areas, the norm is that there are no month names, and days are numbered, 1-365. A date is written “Day#, Year#,” as in 122-1116 – which would be the one hundred and twenty-second day of year 1116 of the Third Imperium.
Our campaign began on 153-1116, and you arrived on Walston on 170-116, and finished your work there, and then left on 175-1116, and arrived at Flammarion on 191-1116. You were ready to leave there on 198-1116, meaning that about a month and a half have gone by in the game already.
A unique facet of Traveller campaigns is that a good amount of in-game time will pass, due to the length of hyperspace jumps. Getting to Tarsus is going to take 6 weeks of jump time, plus some days here and there between them. I’ll say at least 50 days to get there, given time to reload ship’s stores…meaning that by the time you arrive at ‘adventure site #2’ over three months will have elapsed.