Hi atissin welcome!
Its great u want to get ur lo on a routine. SInce ur lo has a cold I would leave any routine changes untill she's feeling better, otherwise I could be too much for her to handle.
Can U post ur current routine in the following format:
E what time
A for how long
S what time and for how long
this will help the ladies here to get a better picture of whats going on and they will be able to give u advise.
At around 4 months los on average r ready to be moved onto 4 hour feeding routine, u could concentrate on establishing a good routine with 3 -3.5 hour feeds and then gradually move onto 4 hour. Ur other option is to implement a plan Tracy devised for introducing EASY at 4 month r older in her book 'Baby Whisperer Solves all Your Problems'.
Could u give a bit more info in regards to ur los sleep, ie. how does she settle, what u do r use to get her to sleep, do u have a wind own routine? Do u do a dream feed?