diff --git a/Validity.md b/Validity.md
index 8a35e06..042ff6f 100644
--- a/Validity.md
+++ b/Validity.md
@@ -52,4 +52,36 @@ Please be careful about the format,  there are only `+*d` (for days) and `+*h` (
 
 
 
+### 2.  Set the beginning time of the cert:
+
+
+```
+acme.sh  --issue  -d example.com --dns dns_cf   --valid-from  "2022-04-01T08:10:33Z"
+
+```
+
+The cert time will be valid start from `"2022-04-01T08:10:33Z"`.
+
+You can also use the relative time format:
+
+```
+
+#The cert will be valid after 2 hours:
+
+acme.sh  --issue  -d example.com --dns dns_cf   --valid-from  "+2h"
+
+
+#The cert will be valid after 1 day:
+
+acme.sh  --issue  -d example.com --dns dns_cf   --valid-from  "+1d"
+
+
+```
+
+
+
+
+
+
+