How early would you suppose ancient Judean (and Jewish proselyte) Pilgrims begin making plans for their Passover journeys? Perhaps as early as you start getting ready for Christmas? Putting yourself into the first century pilgrimage question... your answer might not depend on - but may have to contend with - what Roger Beckwith argued in his 2001 book, Calendar and Chronology.
According to the Mishnah, a certain "Rabbi Gamaliel" once wrote a letter to someone in authority, declaring that Passover should be postponed (!) by a month. The Rabbi's reasoning? Lack of girth. From a sampling of local/regional livestock, it seems lambs and turtledoves had not yet grown to the preferable sizes for sacrificing. Also, the spring harvest had not yet produced grain heads of acceptable size. Not to make light, but it should go without saying this Gamaliel was almost certainly a Pharisee.
Now, Beckwith admits this letter may well post-date 70 AD, but suggests that it may not, and even if so, that it likely reflects practice in pre-70 Judea as well. Thus, Roger concludes, Passover was so unfixed it was possible to reschedule the whole festival by a month if the incoming grain wasn't ripening quickly enough. Lambs and turtledoves, perhaps, could have been sized months in advance, but to disapprove grain heads it must have been past January, surely. If not past February. (Anyone?)
These agricultural questions I can't answer, but we can nevertheless consider the same question from another, equally valuable position. In three parts:
(1) How early did Simon of Cyrene NEED to know which month that particular Passover was going to be held in? (2) How much time did Simon require to get himself and his two boys from North Central African coast to Jerusalem, including time required for travel planning in addition to actual self-transportation? (3) How much time did the news take to spread that Jerusalem's authorities had determined WHICH MOON the festival would be held under, that year, in March or in April?
It may not be necessary for us to answer these questions precisely so much as consider their general significance. I find it difficult to believe that Jerusalem before 70 AD - especially with the Saducees leading under Annas & Caiaphas - would have allowed such nit-picking questions to amend Passover's date *after* the first of the year. If Simon of Cyrene needed a month's travel time, minimum, just to arrive, and if the scheduling announcement required approximately the same lead time, then 'Rabbi Gamaliel' would have needed to CONCLUDE his successful calendar protest by mid-January at the very latest. This seems unlikely, I must say, for a number of reasons.
Granted, I've only sketched out these reasons here, and in my earlier posts (October, 2009). Also November '09 here and here.) Someone else should try a more thorough logistical, financial and agricultural analysis of the possibilities here. However, it also goes to show that general skepticism about Gospel Chronology should be as doubtable as overconfidence. Just because Roger Beckwith built a head of uncertainty around this issue since 1996, doesn't mean we should be quite so un/certain of what Beckwith asserted so confidently.