There are several points at which the procedure may be put on hold.
A) After pelleting cells following formaldehyde fixation and washes, you can freeze the cell pellet at -80°C.
B) After making the lysate, you can freeze the lysate at -80°C.
C) After sonication, you can store the chromatin in aliquot and store at -80° C.
D) After DNA isolation prior to DNA purification, you may store DNA at -20°C or 4°C.