Fix bad ts_init value for IB weekly and monthly bar

Credit to @Endura2024 (#2355).

Author: cjdsellers

RELEASES.md

@@ -80,6 +80,7 @@ Released on TBD (UTC).
 - Fixed sub command issue in some adapters (#2343), thanks @faysou
 - Fixed `bypass_logging` fixture to keep log guard alive for entire test session
 - Fixed time parsing for IB adapter (#2360), thanks @faysou
+- Fixed bad `ts_init` value in IB weekly and monthly bar (#2355), thanks @Endura2024
 
 ### Documentation Updates
 - Added backtest clock and timers example (#2327), thanks @stefansimik

nautilus_trader/adapters/interactive_brokers/client/market_data.py

@@ -543,8 +543,8 @@ async def _convert_ib_bar_date_to_unix_nanos(self, bar: BarData, bar_type: BarTy
         int
 
         """
-        if bar_type.spec.aggregation == 14:
-            # Day bars are always returned with bar date in YYYYMMDD format
+        if bar_type.spec.aggregation in [14, 15, 16]:
+            # Day/Week/Month bars are always returned with bar date in YYYYMMDD format
             ts = pd.to_datetime(bar.date, format="%Y%m%d", utc=True)
         else:
             ts = pd.Timestamp.fromtimestamp(int(bar.date), tz=pytz.utc)