I would start in Isinliví, and I would also stay a night there before starting the hike to Chugchilan. The bus from Latacunga to Isinlivi leaves at 11 on Saturdays and at 13 other days (at least it did in 2011 and 2012). It takes around 2,5 hours.
The first time I hiked from Isinlivi to Chugchilan I had got a good description from Llulu Llama (where I stayed the first time) and the second time I tried to take another route (without description), but ended up crossing the river at the same place as the previous year.
The easiest hike is between Chugchilan and Quilotoa, because when I visited the second time they had put up signs along the trail. It is also the hike where you will meet most people.
The trickest was the hike from Quilotoa to Tigua. I did it alone in 2011 and didn’t have any description of where to go, but asked farmers along the way (if I saw any). I absolutely didn’t take the shortest way. Tigua is situated along the Latacunga – Quevedo road and there, there are at least buses passing by every hour.
I have made tips about the hikes, accommodation, transport and what to pack on these travel pages:
Isinlivi: http://members.virtualtourist.com/m/3fbdb/184089/
Chugchilan: http://members.virtualtourist.com/m/3fbdb/184ac0/
Quilotoa: http://members.virtualtourist.com/m/3fbdb/1839f3/
Tigua: http://members.virtualtourist.com/m/3fbdb/22ab7b/
I didn't visit in March. It was July both times when I hiked in the area.