Ok - well that's not going to be a one-line answer! Here are some thoughts!:
# To state the obvious - this is a 4000m peak so you will feel the altitude if you go too quick. The only safeguard if you can call it that, is that the two Toubkal refuges are around 3200m so you can sleep there without feeling major affects of AMS. Safe absolute minimum times of ascent are 3 days out and back from Marrakech - 4 days better to allow for an acclimatisation peak to be climbed.
# The fitter you are obviously the better and the easier for yourself. If you are not used to 6-7 hour days in the mountains and you are trying to climb Toubkal in 3 days or even less round trip from Marrakech then you will suffer! Be kind to yourself and get some walking in before you embark on this!
# "Winter" is really end of November to mid April +/- 2 weeks both sides. This means that during this time you will either have to carry all your own equipment and food up to the refuge or engage porters as mules will only go as far as the snowline which in mid-winter is down at Sidi Chamharouch and sometimes lower.
# At the refuge you either have to cook your own food or pay someone up at the refuge to this for you (or you can arrange with a local guide in Imlil or professional mountaineering company like ours to sort this out for you in advance). The Mouflon Toubkal refuge can provide food / meals for you if you order in advance.
All of the comments below are based on ascents in Winter!
A. Climbing Toubkal in winter generally requires wearing crampons and using a walking ice-axe. However the ascent (by either the south or north cwm routes -see point 8 below) is not technical and so you do not necessarily need prior experience using an axe or crampons if you are going with a reputable / qualified mountain guide. (We would not recommend you climbing Toubkal in winter without a winter experienced guide if you do not have prior winter walking / climbing experience).
B. The normal un-acclimatised but reasonably mountain fit individual will take around 6 hours walking from Imlil (1750m) to the refuges (around 3200m). The return leg down will take around 4 hours. These times depend on the snowline and depth of untracked snow. I remember early January '08 when it was an epic to descend due to a huge volume of new snow - right down to Imlil in fact. Also if there is any ice en-route it can make for some delicate foot placements.
C. There is 1 frequented and 1 far less frequented route from the refuges. The standard frequented South Cwm route (prominent right-hand valley in photo) and the slightly longer, steeper & much less frequented North Cwm route (prominent left-hand valley in photo). Approx 90% or more ascents are made by South Cwm route. I have lost count of the number of days I have done the North Cwm route with no other parties present yet on arriving at the summit it could be like any popular Alpine summit in terms of numbers! Local "guides" contracted in Imlil rarely if ever take the North Cwm route as it is longer, steeper and more committing in winter (that said it is still "only" Alpine grade F+ / PD-). The same can be said of virtually all the other (UK) guiding companies as they generally contract Moroccan guides to lead the trip who prefer the ease and less committing nature of the South Cwm route.
D. In terms of times of ascent/descent (round trip out and back from the refuges) for the South Cwm, it is anywhere 6-8 hours depending on fitness, peoples abilities on snow and the quality / depth of (un)tracked snow.North Cwm route up and South Cwm route down (i.e. a traverse of the peak) is usually anywhere 7-9 hours.
E. Both routes have a steep start from the refuge - the North Cwm route steepest of all. The North Cwm route initially involves a traverse across 35 degree slopes and then straight up a steep slope before gaining the relative flatness of the actual cwm. Have your axe at the ready doing this traverse to arrest any slide - although the run-out is generally not serious it can feel like a long way down to the river bed!Both routes exit onto the relevant col (South Cwm - South Col; North Cwm - North Col) before the climber is required to ascend the relevant ridge to the summit.
The North Ridge is steeper and requires some delightful easy scrambling and a true feeling of an Alpine ridge. It is generally objective free of danger and other than coping with a strong side wind it is generally a safe line.
The South Ridge can be taken direct or avoided by traversing below (western side). Be aware however that this traverse takes the climber above a cliff band - to slide here would not be good! Again depending on the snow conditions, it is often airier but safer to stay on the ridgeline proper rather than do the traverse.
F. As with all winter conditions, you should have axe / crampons (and know how to use them! - but see point A above), winter boots, a rucsac with the usual safety bits and pieces (down jacket / spare food / water / anorak etc) and be mountain aware! Turn back if in doubt about things, your breathing, the weather etc......