One side of my house is overlook an Alleway (cars can drive). I want to build a fence similar to this one (click on the link below please)

http://tinypic.com/r/24n2yja/8

My house is in similar situation of the picture above (instead of the green, my house is there).

Of course the fence is going to be build on my property side. I want a protection fence like the one in the picture because I am afraid in the Winter cars might slip and hit my house.

I started working and dig to install the Posts. There will be 6-8 post and the distance between them is 6' feet. My question, should I install the first post (put the gravel first and then concorete) and then wait to dry and then try to install pther post so I can use the first one as a bench mark when I try to make sure they all post are layed on the same level and the hight are the same. I thought it is good idea to do that. What do you think

Thanks a lot.