It means all the babies hatch close to the same time. Mother robins may start incubating their eggs during the evening after the second egg is laid, or after all the eggs are laid. They sit on the eggs for 12 to 14 days.ost birds lay their eggs at sunrise, but NOT robins! They lay their eggs at mid-morning. That's several hours later than most birds lay eggs. For robins, this makes good sense.