The Jesus Seminar places the dates at:

John the Baptist's death at ca. 27 CE. (So if anybody tries to tell you that the books that bear his name were written by him, the onus is on them to provide some pretty darned good documentation.)

Jesus' death, ca. 30 CE.

Saul of Tarsus, chief founder of gentile Christianity lived 30-60 CE., and wrote his epistles 50-60 CE.

The Gospel of Q (first edition, about 50-60 CE.)

The Gospel of Thomas (first edition, about 50-60 CE.)

The Gospel of Mark; the first narrative gospel (first edition about 70 CE.)

Gospel of Matthew, incorporating Mark and Q, about 85 CE.

Gospel of Luke, incorporating Mark and Q, about 90 CE.

Gospel of Peter (first edition, probably 50-100 CE.)

Egerton Gospel (probably 50-100 CE.)

Gospel of John, incorporating the Gospel of Signs (60-70 CE.), about 90 CE.

Gospel of Mark, canonical edition (about 100 CE.)

Gospel of John, third edition (insertions and additions), 100-150 CE.

Emergence of four "recognized gospels," 150-325 CE.

First surviving copies of "Bibles," about 300-350 CE.)