move blockstore read after tick height check

poh/src/poh_recorder.rs

@@ -571,6 +571,11 @@ impl PohRecorder {
             return PohLeaderStatus::NotReached;
         };
 
+        if !self.reached_leader_tick(my_pubkey, leader_first_tick_height_including_grace_ticks) {
+            // PoH hasn't ticked far enough yet.
+            return PohLeaderStatus::NotReached;
+        }
+
         if self.blockstore.has_existing_shreds_for_slot(next_poh_slot) {
             // We already have existing shreds for this slot. This can happen when this block was previously
             // created and added to BankForks, however a recent PoH reset caused this bank to be removed
@@ -580,11 +585,6 @@ impl PohRecorder {
             return PohLeaderStatus::NotReached;
         }
 
-        if !self.reached_leader_tick(my_pubkey, leader_first_tick_height_including_grace_ticks) {
-            // PoH hasn't ticked far enough yet.
-            return PohLeaderStatus::NotReached;
-        }
-
         assert!(next_tick_height >= self.start_tick_height);
         let poh_slot = next_poh_slot;
         let parent_slot = self.start_slot();