diff --git a/.changelog/5462.fixed b/.changelog/5462.fixed
new file mode 100644
index 00000000000..280c3181e45
--- /dev/null
+++ b/.changelog/5462.fixed
@@ -0,0 +1 @@
+`opentelemetry-sdk`: fill every bucket of `SimpleFixedSizeExemplarReservoir` before random sampling
diff --git a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/_internal/exemplar/exemplar_reservoir.py b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/_internal/exemplar/exemplar_reservoir.py
index afe2dcba38a..dd0a956c9dd 100644
--- a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/_internal/exemplar/exemplar_reservoir.py
+++ b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/_internal/exemplar/exemplar_reservoir.py
@@ -255,10 +255,11 @@ def _find_bucket_index(
         attributes: Attributes,
         context: Context,
     ) -> int:
-        self._measurements_seen += 1
         if self._measurements_seen < self._size:
+            self._measurements_seen += 1
             return self._measurements_seen - 1
 
+        self._measurements_seen += 1
         index = randrange(0, self._measurements_seen)
         if index < self._size:
             return index
diff --git a/opentelemetry-sdk/tests/metrics/test_exemplarreservoir.py b/opentelemetry-sdk/tests/metrics/test_exemplarreservoir.py
index 9c5bf69bdb3..7078bd41424 100644
--- a/opentelemetry-sdk/tests/metrics/test_exemplarreservoir.py
+++ b/opentelemetry-sdk/tests/metrics/test_exemplarreservoir.py
@@ -63,6 +63,28 @@ def test_filter_attributes(self):
         self.assertIn("key1", exemplars[0].filtered_attributes)
         self.assertNotIn("key2", exemplars[0].filtered_attributes)
 
+    def test_fills_every_bucket_before_sampling(self):
+        # The first `size` measurements must each land in their own bucket,
+        # otherwise the reservoir never reaches its configured capacity.
+        for size in (1, 2, 4, 10):
+            with self.subTest(size=size):
+                reservoir = SimpleFixedSizeExemplarReservoir(size)
+
+                for value in range(size):
+                    reservoir.offer(
+                        float(value),
+                        time_ns(),
+                        {"attribute": "value"},
+                        Context(),
+                    )
+
+                exemplars = reservoir.collect({})
+                self.assertEqual(len(exemplars), size)
+                self.assertEqual(
+                    sorted(exemplar.value for exemplar in exemplars),
+                    [float(value) for value in range(size)],
+                )
+
     def test_reset_after_collection(self):
         reservoir = SimpleFixedSizeExemplarReservoir(4)