fix: if first run, show message

bin/postinstall.js

@@ -1,3 +1,5 @@
+#!/usr/bin/env node
+
 function main() {
   if (process.env.SUPPRESS_SUPPORT) {
     return;
@@ -15,7 +17,7 @@ function main() {
     const conf = new Configstore(pkg.name);
     const last = conf.get('lastCheck');
 
-    if (now - week > last) {
+    if (!last || now - week > last) {
       console.log('\u001b[32mLove nodemon? You can now support the project via the open collective:\u001b[22m\u001b[39m\n > \u001b[96m\u001b[1mhttps://opencollective.com/nodemon/donate\u001b[0m\n');
       conf.set('lastCheck', now);
     }