Traditionally, the Church has set the day of the crucifixion on Friday. This may be because of the scriptures that say He was crucified on “the day before the Sabbath” (Mk 15:42 et al.) However, there is another Sabbath – the first day of the Feast of Unleavened Bread which is the day after Passover. (Ex 12:16; Lev 23:7; Num 28:18) So the referenced Sabbath may be the “High Sabbath” of the Feast of Unleavened Bread.
A clue is given in Matthew 12:39-40: “But He answered and said to them, "An evil and adulterous generation craves for a sign; and yet no sign will be given to it but the sign of Jonah the prophet; for just as JONAH WAS THREE DAYS AND THREE NIGHTS IN THE BELLY OF THE SEA MONSTER, so will the Son of Man be three days and three nights in the heart of the earth.”
The latest Jesus could have been resurrected is the following Sunday because the women came to the tomb and found it empty: “Now after the Sabbath, as it began to dawn toward the first day of the week, Mary Magdalene and the other Mary came to look at the grave. … "He is not here, for He has risen, just as He said. Come, see the place where He was lying" – Matthew 28:1,6. If the “sign of Jonah” is meant to be taken literally, then the latest that Jesus could have been crucified is Thursday (Day/Night 1: Thursday-Friday, Day/Night 2: Friday/Saturday, Day/Night 3: Saturday/Sunday.)
It is also possible that He rose sometime earlier on Saturday (since there weren’t witnesses on that day) so it could be that He was crucified on Wednesday. However, if this is the case, He would have most likely have had to enter Jerusalem on Saturday, which would be a violation of the Sabbath because of His riding of the donkey.
Conclusion: If the “sign of Jonah” is meant literally, it is most likely that Jesus was crucified on Thursday.