I don't have the most detailed advice, but first, the champ. Do you have Ancient Shadows enabled in the lobby? And are you setting yourself to 'normal' or 'normal+champion'?
Attack with (preferably reclaim-immune) ships with a bonus to leech ships' hull type, or with turrets with similar bonuses.
Riot starships can be quite helpful, or not too helpful besides having a sheild to tank damage, depending on how you outfit their modules.
If you aren't sure how many turrets to use and have lots of available energy, build all of your per-planet turrets to defend your imprtant things, and forcefield wormholes that lead to less defended systems.
If you're confident in your defenses, bring all your ships along. After all, they can pull back if you can get back.
You need a purpose to take planets (and thus AIP) after you sort out your immediate surroundings in the beginning. Is there an ARS you like? Could be worth the new ships. Advanced factories or starship constructors? Either hack them or take-and-hold the planet for their usefulness. Fabricators are also nice. Turret controllers, maybe? Perhaps free the dyson sphere planet and let it bother the AI a bit. Useful chokepoint planets for defensive enplacements, and so on.
Define 'time constraints'. Do you have auto-aip enabled, or something else? A normal game without any of the minor factions or plots that have those kind of effects (like auto-aip, or spire civ leaders, or one of the shark plot options) is limited only by how far you push the AIP. Eventually you will push it too high, but that happens by you making it so, not by a time limit pushing things ever forward. (or if you try to hack too far into negative HaP, which will draw much more direct doom) Pause is entirely usable for commands.