Reason I was able to lose I think 20kg in 4 weeks once was cause I was eating 1200 Calories a day, 20km in walking and I worked on my feet all day too.
That seems to stressful to me at this present moment, so taking it a little easier, 2 x 5km a day should be suffice for a couple of weeks.
I think you are doing a more realistic way this time
You have inspired me to go for a 5km walk today. We have a lake nearby and to walk around it twice is 5km. It takes me 30 min for walk around once so should take me an hour