when to hesitate and when not

The gemara (Shaboos 134) says that one is allowed to be mechalel shabbos to wash a baby on the third day after milah.  Some Rishonim hold that this means davka on the third day, as it is on that day that the pain is most intense.  Other Rishonim hold that it means all days up to and inclusive of the third day.  

My SIL in Eretz Yisrael is learning Shabbos and pointed out a very interesting Meiri.  We read in parshas vayishlach (34:25):

 וַיְהִי בַיּוֹם הַשְּׁלִישִׁי בִּהְיוֹתָם כֹּאֲבִים וַיִּקְחוּ שְׁנֵי⁠ בְנֵי⁠ יַעֲקֹב שִׁמְעוֹן וְלֵוִי אֲחֵי דִינָה אִישׁ חַרְבּוֹ וַיָּבֹאוּ עַל⁠ הָעִיר בֶּטַח וַיַּהַרְגוּ כׇּל⁠ זָכָר.

If the first two days after milah are as painful as the third day, why did Shimon and Levi wait?

The Baalei Tosfos (Daas Zekeinim, Hadar Zekeinim, see also Tur) answer that there were so many people that it took three days to mal the entire city (a bit difficult, as Yehoshua did milah on all those who had been born in the midbar in a single day after Bn"Y crossed the Yarden), or it took three days to convince everyone in the city to do milah.

Meiri (Shabbos 86a, and the Tur also quotes this answer):

 ויהי ביום השלישי בהיותם כואבים כלומר שעדיין היו כואבים וכל שכן שהיו כואבים בראשון ושני אלא שהיו נמלכים בעצמם אם יעשו אם לא יעשו וכשהגיעו לשלישי ודנו בעצמם שאם לא יעשו באותו היום אף הם מתרפאים למחרתו נמנו וגמרו להרגם

Shimon and Levi were uncertain what to do, and debated among themselves for two days.  When the third day came and they realized it was now or never, as the people of Shechem would start to heal the next day, they acted.

My 2 cents: this is the same Shimon and Levi who, with their brothers tacit approval, who immediately wanted to take advantage of the opportunity to kill Yosef once they had him alone, and would have done so if not for the intervention of Reuvain and Yehudah.  No days of deliberation or second thoughts here!

Sadly, this is an all too common story.  When it comes to our aku"m enemies, we klerr back and forth and wring our hands for days deliberating before we finally take action.  However, when it comes to shechting one of our own, the knives are out in an instant and we are at each other's throats without a second thought.  

Baruch Hashem, I think the tide is turning.  We have learned our lesson a bit and we are seeing more achdus in our own camp and more resolve to do what needs to be done to the enemy.