Is it okay for a potential post doc to send an email to professor on the weekend? I am talking with a professor to apply to a postdoc program. I sent a cold email earlier this week and we have exchanged a few emails.
In his last email he sent me some papers to read.
The thing is, I might end up sending my answer on Saturday, after I read the papers. Is this a problem? Should I just send it and wait until Monday for his answer? Maybe send it but include an apology for writing during the weekend? Or should I just wait until Monday to send it?
I usually text everyone during the weekend including my advisor, but I'm not sure if it might be considered rude, and as I do not know the person yet I want to be as careful as possible with etiquette.
Thank you.
Email is a form of asynchronous communication: it doesn't matter when mail is sent, it can be read whenever pleases the recipient.

High-ranking professionals should not sacrifice their operational efficiency to avoid the possibility of lower-ranking professionals feeling stressed, overwhelmed, etc. by out-of-hours emails. High-ranking professionals should make lower-ranking professionals aware of work-life balance. Managers and subordinates should discuss expectations. 

Technology can help. Email should never raise notifications. (They're too numerous and interfere with flows.)  Messaging apps can be segregated: Some for work, others for home. (Signal at work, WhatsApp at home, for instance.) Work apps should only raise notifications during set hours. 

Only individuals can establish their own, "best" work-life balance.