Is a hatch possible

[newpoultryppl2]

I have one broody hen that is sitting on five eggs, but I have 6 to 8 other eggs that I would like to try and hatch out that were laid in the last couple of days do I have to get an incubator or can I hatch them with a heat lamp and a makeshift nest. And how many days will the eggs be okay to still try and hatch before I have to do something

 

[rainbowrooster]

I often keep eggs for 10 days but most people only store them for 7 days. A heat lamp wont work. There is no way to stabilize temperature and humidity.