diff --git a/httpcore/_async/http11.py b/httpcore/_async/http11.py
index 9ee3c6ba..38f4a292 100644
--- a/httpcore/_async/http11.py
+++ b/httpcore/_async/http11.py
@@ -71,7 +71,8 @@ def __init__(
             our_role=h11.CLIENT,
             max_incomplete_event_size=self.MAX_INCOMPLETE_EVENT_SIZE,
         )
-        self._socket_used_at = time.monotonic()
+        # Assuming we were just connected
+        self._network_stream_used_at = time.monotonic()
 
     async def handle_async_request(self, request: Request) -> Response:
         if not self.can_handle_request(request.url.origin):
@@ -177,7 +178,7 @@ async def _send_event(
         bytes_to_send = self._h11_state.send(event)
         if bytes_to_send is not None:
             await self._network_stream.write(bytes_to_send, timeout=timeout)
-            self._socket_used_at = time.monotonic()
+            self._network_stream_used_at = time.monotonic()
 
     # Receiving the response...
 
@@ -229,7 +230,7 @@ async def _receive_event(
                 data = await self._network_stream.read(
                     self.READ_NUM_BYTES, timeout=timeout
                 )
-                self._socket_used_at = time.monotonic()
+                self._network_stream_used_at = time.monotonic()
 
                 # If we feed this case through h11 we'll raise an exception like:
                 #
@@ -294,8 +295,8 @@ def has_expired(self) -> bool:
         # only valid state is that the socket is about to return b"", indicating
         # a server-initiated disconnect.
         # Checking the readable status is relatively expensive so check it at a lower frequency.
-        if (now - self._socket_used_at) > self._socket_poll_interval():
-            self._socket_used_at = now
+        if (now - self._network_stream_used_at) > self._socket_poll_interval():
+            self._network_stream_used_at = now
             server_disconnected = (
                 self._state == HTTPConnectionState.IDLE
                 and self._network_stream.get_extra_info("is_readable")
diff --git a/httpcore/_sync/http11.py b/httpcore/_sync/http11.py
index 6da2fc5d..eecfd33c 100644
--- a/httpcore/_sync/http11.py
+++ b/httpcore/_sync/http11.py
@@ -71,7 +71,8 @@ def __init__(
             our_role=h11.CLIENT,
             max_incomplete_event_size=self.MAX_INCOMPLETE_EVENT_SIZE,
         )
-        self._socket_used_at = time.monotonic()
+        # Assuming we were just connected
+        self._network_stream_used_at = time.monotonic()
 
     def handle_request(self, request: Request) -> Response:
         if not self.can_handle_request(request.url.origin):
@@ -177,7 +178,7 @@ def _send_event(
         bytes_to_send = self._h11_state.send(event)
         if bytes_to_send is not None:
             self._network_stream.write(bytes_to_send, timeout=timeout)
-            self._socket_used_at = time.monotonic()
+            self._network_stream_used_at = time.monotonic()
 
     # Receiving the response...
 
@@ -229,7 +230,7 @@ def _receive_event(
                 data = self._network_stream.read(
                     self.READ_NUM_BYTES, timeout=timeout
                 )
-                self._socket_used_at = time.monotonic()
+                self._network_stream_used_at = time.monotonic()
 
                 # If we feed this case through h11 we'll raise an exception like:
                 #
@@ -294,8 +295,8 @@ def has_expired(self) -> bool:
         # only valid state is that the socket is about to return b"", indicating
         # a server-initiated disconnect.
         # Checking the readable status is relatively expensive so check it at a lower frequency.
-        if (now - self._socket_used_at) > self._socket_poll_interval():
-            self._socket_used_at = now
+        if (now - self._network_stream_used_at) > self._socket_poll_interval():
+            self._network_stream_used_at = now
             server_disconnected = (
                 self._state == HTTPConnectionState.IDLE
                 and self._network_stream.get_extra_info("is_readable")