Back to the OP's question: what time do hens lay?
Well, it takes about 26 hours to "build" an egg, so most hens start their laying cycle in the morning. If they are daily layers, then the next egg would be ready a bit more than a day later, a couple hours later in the day. And the same for the next day, etc. So many hens lay by 7 a.m. one day, 9 a.m. the next, 11 a.m. the third day, and so on and so forth until it's too late to lay that day. So they may skip a day and the cycle begins anew.
The longest amount of time spent in building an egg is 19 hours for the shell, next to the last step of the process. (The last step is coating the completed egg with the "bloom" - the bacteria barrier over the shell.)
Often the glitches in egg creation - especially for new layers - occurs in this lengthy shell-building stage, which is why so many new layers occasionally lay "rubber" or shell-less eggs, or the shells are mis-shapen, or just odd looking. Once their bodies get all the gears in place and in motion (so to speak) the eggs will be just fine.