Fix the logic that was failing to record TTFR (#798)

Author: peachisai

apm-sniffer/apm-sdk-plugin/spring-plugins/spring-ai-1.x-plugin/src/main/java/org/apache/skywalking/apm/plugin/spring/ai/v1/ChatModelStreamInterceptor.java

@@ -63,6 +63,8 @@ public void beforeMethod(EnhancedInstance objInst, Method method, Object[] allAr
             return;
         }
 
+        ContextManager.getRuntimeContext().put(Constants.SPRING_AI_STREAM_START_TIME, System.currentTimeMillis());
+
         ChatOptions chatOptions = prompt.getOptions();
         if (chatOptions == null) {
             return;
@@ -72,8 +74,6 @@ public void beforeMethod(EnhancedInstance objInst, Method method, Object[] allAr
         Tags.GEN_AI_TEMPERATURE.set(span, String.valueOf(chatOptions.getTemperature()));
         Tags.GEN_AI_TOP_K.set(span, String.valueOf(chatOptions.getTopK()));
         Tags.GEN_AI_TOP_P.set(span, String.valueOf(chatOptions.getTopP()));
-
-        ContextManager.getRuntimeContext().put(Constants.SPRING_AI_STREAM_START_TIME, System.currentTimeMillis());
     }
 
     @Override