Scheduling random subset of agents to run task in NetLogo - random

Question

I have been developing a procedure for 'human' agents to move south into a
forest from hours 0600 to 1200 and then leaving the forest from 1200 to 1800.
Currently all of the human agents start walking in at 0600. This creates a wave
effect, but instead I'd like a continuous stream of humans. One option I
thought of was to have a random subset of them begin moving at 0600, another
subset begin at 0700, etc, until 1200 when all of them turn around and go back
out. Alternatively, it may be nice to generate a new set of 'humans' at each of
the morning times (i.e., 0600,0700,0800,0900,1000,1100) to move in, instead of
selecting a random subset. I've been stuck on this for awhile and any help
would be much appreciated. I have the code below.
--Neil
to setup
ca
clear-all-plots
clear-output
set typeAgro 1 ;this is Agricultural land outside forest
set typeTrop 2 ;this is tropical forest
ask patches
[ set habitat typeAgro ]
ask patches with [pycor <= 300] ;all patches south of y-coord 300 is tropical
forest
[ set habitat typeTrop]
create-humans number-humans ;on a slider from 100 to 200
[ setxy random-xcor 310 ; start humans in agricultural land just north of
tropical forest
if any? turtles-on patch-here
[ setxy random-xcor 310 ]
set morning 6
set midday 12
set afternoon 18
set midnight 24
set step-size 50
set color white
set size 10
set shape "person" ]
reset-ticks
end
to go
tick
ask humans [move-humans] ; humans moving into the forest
end
to move-humans
let hour ticks mod midnight ; sets the ticks on 24 hour day
if morning <= hour and hour < midday [ ; from 0600 to 1200 people move into
forest
set heading (random-normal 180 30)
fd random-normal step-size 4
]
if midday <= hour and ycor < 310 [ ; from 1200 to 1800 people move out of the
forest
set heading (random-normal 360 30)
fd random-normal step-size 1
]
end