Monthly schedule varies dramatically, and there seems to be no rhyme nor reason to what your roster will be.
For example, I know two ab-initio crew who have just started flying. One had excellent first roster, full of layovers, like SIN, CMN, LHR, CDG, CMB, etc, etc.
The other had only (mainly) turnaround flights, to BEY, CAI, AMM, ISB.....et, etc.
In both cases, the first "observer" flights were short turnarounds to DXB and AUH respectively, immediately followed on the roster by slightly longer turnarounds, like BOM or ISB, etc.
Layover durations vary depending on the day of the week that you fly, but are "generally" as follows (A SAMPLE ONLY):
LGW - 24 HOURS STANDARD
LHR - 24 HOURS STANDARD / 36 HOURS MAX / 18 HOURS MIN
CMN - 48 HOURS STANDARD
DAC - 36 HOURS STANDARD
CMB - 24 HOURS STANDARD / 36 HOURS MAX / 12 HOURS MIN
SIN - 9 DAYS MAX (INCLUDES 3 FULL DAYS IN CEBU) / 2 DAYS MIN
KUL - 24 HOURS MIN / 72 HOURS MAX
DXB - MAINLY TURNAROUNDS OR A 4 HOURS LAYOVER
BAH - DITTO
AUH - DITTO
MUC / FRA - 24 HOURS STANDARD / 48 HOURS MAX
ZRH / VIE / MAN - SAME AS ABOVE
MXP / FCO / MAD - 24 HOURS MIN / 36 HOURS MAX
KIX - 24 HOURS MIN / 48 HOURS MAX
ICN / PEK - AS ABOVE
MLE - 24 HOURS MINIMUM / 48 HOURS MAXIMUM
IST - DITTO
ATH - DITTO
TUN/ALG - 48 HOURS / 72 HOURS
The above is to the best of my knowledge. Others may be able to correct my errors.